LCL-Filter Inductors and Capacitors as Test Load for Rescue Battery Capacity
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Solution Overview
Problem
Current automatic rescue operation systems for elevators are complex, expensive, and provide unreliable power after a power failure, often resulting in insufficient battery capacity for rescue operations, which can lead to failed rescue attempts due to undetected battery degradation.
Innovation Solution
A method using the LCL-filter's inductors and capacitors as a test load to assess the capacity of the drive rescue battery without external equipment, allowing for periodic testing without intervention from the elevator controller, ensuring the battery has sufficient capacity for rescue operations through a series connection and modulated switching of the rectifier circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external load resistors or braking resistors are used to test battery capacity, then the battery capacity can be assessed, but the system complexity and cost increase
Solution Approach 1:
The LCL-filter components (inductors and capacitors) that are already present in the power conversion system are made to serve dual purposes: their primary function during normal operation and as a test load for battery capacity measurement. This eliminates the need for separate external test equipment, reducing system complexity while maintaining measurement capability.
Solution Approach 2:
The system uses its own existing components (LCL-filter inductors and capacitors) to perform the battery testing function without requiring external testing equipment. The inductors and capacitors essentially test themselves as a load, leveraging the system's existing infrastructure for the measurement task.
2Measurement precision
If the motor is used as test load for battery capacity testing, then battery capacity can be measured, but energy efficiency decreases due to motor operation requirements
Solution Approach 1:
The testing function is extracted from the motor operation context and implemented separately using the LCL-filter components as the test load. This allows battery capacity measurement without requiring the motor to operate, thereby eliminating the energy efficiency losses associated with motor testing while maintaining accurate measurement capability.
3Reliability
If periodic battery testing is implemented, then battery capacity sufficiency can be ensured, but system downtime increases
Solution Approach 1:
The system implements periodic battery capacity testing at scheduled intervals rather than continuous monitoring or random testing. This periodic approach ensures battery sufficiency is maintained while minimizing the total time lost to testing operations, as tests are concentrated at specific periods rather than continuously disrupting operation.
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 provides a simple, reliable, and energy-efficient method to ensure the drive rescue battery's capacity is sufficient for rescue operations, allowing for scheduled testing and timely maintenance, reducing the risk of rescue operation failures.
Implementation Method 1
using inductors and capacitors of the LCL-filter, each of which being connected to the first or second phase, as a test load for testing the capacity of the drive rescue battery
Implementation Method 2
the frequency converter comprises a rectifier circuit for providing a DC supply voltage
Implementation Method 3
using inductors and capacitors of the LCL-filter... to form a series connection as the test load
Implementation Method 4
using inductors and capacitors of the LCL-filter, each of which being connected to the first or second phase
Data Source
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AI summary
The invention relates to a method for testing a capacity of a drive rescue battery (10) for driving an electric motor (9) of a transportation system in a rescue operation mode, wherein in normal operation mode AC means (2) supply power over first (P1), second (P2) and third phases (P3) via a low pass LCL-filter (4) to a frequency converter (8) for driving the electric motor (9), wherein the frequency converter (8) comprises a rectifier circuit (5) for providing a DC supply voltage. The method comprises the steps: - disconnecting the LCL-filter (4) from the AC mains (2); - using inductors (L2, L2') and capacitors (C1, C2) of the LCL-filter (4), each of which being connected to the first (P1) or second phase (P2), as a test load for testing the capacity of the drive rescue battery (10), wherein the inductor (L2) of the LCL-filter (4), which is connected to the first phase (P1) and downstream of the capacitor (C1) of the LCL-filter (4) connected to the first phase (P1), to the rectifier circuit (5), the capacitors (C1, C2) of the LCL-filter (4) connected to the first (P1) and second phases (P2), and the inductor (L2') of the LCL-filter (4) which is connected to the second phase (P2) and downstream of the capacitor (C2) of the LCL-filter (4) connected to the second phase (P2), to the rectifier circuit (5) form a series connection as the test load; and - determining at least one value of a voltage or a current of the drive rescue battery (10) resulting from the test load. Other aspects of the invention are a software program realizing the method and a testing arrangement for testing the capacity of the drive rescue battery (10).