Multi-Stator Linear Induction Elevator for CM Noise Reduction
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Solution Overview
Problem
Traditional self-propelled elevator systems face issues with electromagnetic interference (EMI) due to the switching of power electronic devices, particularly common-mode (CM) noise, which can damage motor bearings and windings, and result in undesirable sound, noise, and vibration.
Innovation Solution
A multi-phase linear induction machine is implemented, comprising armatures and stators within the hoistway that generate electromagnetic fields to propel elevator cars without mechanical contact, utilizing power electronics to control current flow and minimize CM noise through a three-phase system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If power electronic devices are used to control current flow in self-propelled elevator systems, then motor efficiency and autonomous operation are improved, but electromagnetic interference and common-mode noise increase causing damage to motor bearings and windings
Solution Approach 1:
A common-mode filter is introduced as an intermediary component between the power electronic devices and the motor to block common-mode noise and electromagnetic interference while allowing normal operation. The filter acts as a mediator that preserves the benefits of power electronic control while eliminating their harmful effects.
Solution Approach 2:
The patent acknowledges that power electronic switching necessarily generates EMI and CM noise, but converts this unavoidable harm into a design consideration by implementing specific filtering solutions. The harmful electromagnetic effects are transformed into a controlled parameter that can be managed through proper filter selection and placement.
2Reliability
If traditional tension members like ropes and cables are used, then elevator car movement is reliable, but the system is not self-propelled and requires mechanical contact
Solution Approach 1:
The patent replaces the traditional mechanical rope-and-pulley system with an electromagnetic propulsion system using linear induction motors. This substitution eliminates mechanical contact, reduces maintenance requirements, and enables self-propelled operation while maintaining reliability through advanced control systems.
3Object-generated harmful factors
If multi-phase linear induction machine with multiple stators is implemented, then silent and vibration-free operation is achieved, but device complexity and control requirements increase
Solution Approach 1:
The motor system is divided into multiple independent stator phases that can be controlled separately. This segmentation allows for precise control of electromagnetic forces to minimize vibration and noise while maintaining propulsion efficiency. Each stator phase can be independently optimized to reduce harmful emissions.
Solution Approach 2:
The patent employs multi-phase control with adjustable current frequencies and amplitudes to optimize motor operation. By changing electrical parameters dynamically, the system achieves silent and vibration-free operation while managing the complexity through sophisticated control algorithms.
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
The solution effectively reduces CM noise concerns, allowing for silent, vibration-free operation and autonomous elevator car movement, while maintaining motor efficiency and preventing damage from EMI, enabling reliable and quiet self-propelled elevator systems.
Implementation Method 1
Each of the stators are configured to conduct electrical current therethrough and to generate an electromagnetic field in response to the current. The electromagnetic field induces eddy currents that flow through the at least armature to generate a magnetic force which moves the elevator car through the hoistway.
Implementation Method 2
The electromagnetic field induces eddy currents that flow through the at least armature to generate a magnetic force
Data Source
AI summary
A multi-phase linear induction machine includes at least one armature which can be disposed in an elevator hoistway and is configured to electrically conduct electromagnetic energy, and a plurality of stators which can be coupled to an elevator car that is configured to travel through the hoistway. Each of the stators are configured to conduct electrical current therethrough and generate an electromagnetic field in response to the current. The electromagnetic field induces eddy currents that flow through the at least armature to generate a magnetic force to move the elevator car through the hoistway.