Elevator Drive Motion Feedback Control
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Solution Overview
Problem
In emergency situations, elevators face challenges in moving to a landing safely without consuming excessive energy, as existing methods either consume too much power or fail to move due to balance issues between the car and counterweight, leading to potential speed increases.
Innovation Solution
An elevator drive apparatus with a controller that detects the electrical operation amount of the drive unit, compares it to a threshold, and applies the brake when exceeded, using current or voltage as motion feedback to control the speed, ensuring safe and controlled movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the brake is cycled/pulsed using a default frequency to limit elevator car speed, then the speed of the elevator car is controlled, but the energy consumption increases significantly and battery lifetime is compromised
Solution Approach 1:
The system uses feedback from current sensors to detect the actual movement of the elevator car. The controller monitors the current drawn by the motor during brake release and uses this feedback information to determine whether the car has moved sufficiently before reapplying the brake, replacing the fixed default frequency approach with an adaptive feedback-based control strategy.
Solution Approach 2:
The brake cycling frequency is made dynamic rather than static. The system adjusts the brake release duration and reapplication timing based on real-time conditions such as the detected current magnitude and direction, which reflect the actual car movement status. This dynamic adaptation optimizes energy consumption while maintaining speed control.
2Speed
If the brake cycle time is prolonged to allow elevator car movement when car and counterweight are close to balance, then the car can move, but the speed of the elevator car may increase too much in case of high unbalance
Solution Approach 1:
The system continuously monitors the current drawn by the motor during brake release. By analyzing the magnitude and direction of this current, the controller receives real-time feedback about the car's movement status and speed tendency, enabling it to adjust the brake reapplication timing to prevent excessive speed while ensuring movement when needed.
Solution Approach 2:
The system changes the operational parameters of the brake control based on detected conditions. When the current indicates the car is moving slowly or not at all (suggesting near-balance conditions), the system prolongs the brake release duration. When current indicates rapid acceleration (suggesting high unbalance), the system shortens the release duration, thus adapting the parameter to maintain safe speed control.
3Ease of operation
If the brake is released to allow elevator car movement using imbalance between car and counterweight, then the car can advance to the nearest door zone, but excessive energy is consumed and battery lifetime is reduced
Solution Approach 1:
The system uses current sensors to provide feedback on the actual movement of the elevator car during emergency operation. The controller monitors this feedback to determine when the car has moved sufficiently toward the door zone, allowing it to reapply the brake at optimal moments and avoid unnecessary prolonged brake release that would waste energy.
Solution Approach 2:
The system employs periodic brake release and reapplication cycles during emergency operation, but the timing and duration of these periodic actions are optimized based on feedback. Rather than continuous brake release or fixed-frequency cycling, the system uses measured intervals adapted to the actual car movement, reducing energy consumption while maintaining the ability to reach the door zone.
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 reliably limits the elevator's speed during emergencies, conserving energy and preventing excessive speed, allowing safe movement to a landing even when machinery is not observable.
Implementation Method 1
The electrical operation amount may be a current and/or a voltage generated by the rotating electrical machine due to a movement of the elevator car after releasing the brake device
Data Source
AI summary
An elevator drive apparatus is described which includes a drive unit for driving an elevator car, a brake device for braking a motion of the elevator car, a detector for detecting an electrical operation amount of the drive unit, and a controller. The controller is configured to release the brake device, to compare the detected electrical operation amount with a threshold, and to apply the brake device when the detected electrical operation amount exceeds the threshold. In this way, it is ensured that a speed of the elevator car in case of a rescue situation is within a safety limit.