Elevator Run Profile Adaptation for Limited Power Supply
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Solution Overview
Problem
Conventional elevator systems face issues with emergency stops due to power shortages, particularly in single-phase battery-supplemented systems, leading to inefficient operation and increased journey times, especially with varying loads.
Innovation Solution
An elevator system that measures current through the motor to determine predicted power demand, adjusting run profile parameters based on available power, ensuring power consumption does not exceed availability by adjusting speed, acceleration, and jerk before the elevator car moves, using a controller to optimize operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the elevator system operates with a predetermined run profile at full power, then the journey time is reduced and productivity is improved, but the power consumption may exceed the available power from the grid or battery, causing emergency stops and reliability issues
Solution Approach 1:
The run profile parameters (acceleration, speed, jerk) are dynamically adjusted based on real-time power availability from the grid or battery. The controller continuously monitors power sources and modifies the elevator car's motion profile to match available power, preventing emergency stops while optimizing journey time under each power condition.
Solution Approach 2:
The system changes operational parameters (acceleration rate, maximum speed, jerk limits) of the run profile based on the detected power availability. When battery power is available, the system uses lower acceleration and speed parameters; when grid power is available, it uses higher parameters to reduce journey time.
2Adaptability or versatility
If the elevator system uses a single-phase power supply with battery supplementation, then the system can operate during grid outages, but the maximum power limit is constrained by battery capacity, requiring reduced operating speeds and increasing journey times
Solution Approach 1:
The elevator system is designed to operate with multiple power sources (grid and battery) and automatically switches between them based on availability. The controller detects which power source is active and adjusts the run profile parameters accordingly, allowing the system to maintain functionality across different power conditions while optimizing performance for each mode.
3Reliability
If the run profile parameters are adjusted in real-time based on power availability, then the power consumption is optimized to match available power, but the system complexity increases due to additional sensing and control requirements
Solution Approach 1:
The controller continuously monitors the status of power sources (grid and battery) and uses this feedback to adjust run profile parameters in real-time. The system detects power availability and automatically modifies acceleration, speed, and jerk parameters to ensure power consumption does not exceed available power, creating a closed-loop control system.
4Productivity
If the elevator car accelerates at high rates to reduce journey time, then the productivity is improved, but the power demand during acceleration exceeds the available battery power, causing emergency stops
Solution Approach 1:
The controller determines power availability from the battery before the elevator car begins movement. Based on this preliminary assessment, the system pre-adjusts the run profile parameters (acceleration rate, maximum speed) to ensure that the power demand during acceleration and constant speed phases does not exceed the battery's available power capacity.
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 approach prevents emergency stops and optimizes journey times by dynamically adjusting parameters to match available power, allowing efficient operation even with varying loads and power sources.
Implementation Method 1
a current sensor arranged to measure a current through the motor representative of a torque applied by the motor to the drive sheave
Implementation Method 2
a motor arranged to rotate the drive sheave so as to move the elevator car according to a predetermined run profile
Data Source
Figure 1a~1c
Figure 2
Figure 3
AI summary
An elevator system comprising an elevator car (100) and a drive unit (109) comprising a drive sheave (102) and motor (111) arranged to move the elevator car (101) according to a predetermined run profile. The elevator system (101) also comprises one or more power sources (115; 117) for providing power to the drive unit (109), a current sensor (113) and a controller (123). The controller (123) is configured to cause the current sensor (113) to measure a current through the motor (111) while the elevator car (101) is held stationary at the landing by the motor (111) and/or during an initial phase of the run profile, to determine an available power from the one or more power sources (115; 117), and to determine a predicted power demand for the drive unit (109) based on the measured current and one or more parameters of the predetermined run profile. The controller (123) is also configured to determine whether the predicted power demand is greater than the available power from the one or more power sources (115; 117), and if so, to adjust one or more parameters of the predetermined run profile while the elevator car (101) is held stationary at the landing by the motor (111) and/or during the initial phase.