Linear Motor Mover with Extracted Magnets
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Solution Overview
Problem
Existing electric linear motors with stators comprising windings and/or permanent magnets are expensive and heavy, particularly for long trajectories, and require complex and costly power electronics, leading to high friction losses and reduced efficiency.
Innovation Solution
A method for controlling an electric linear motor with a stator beam having ferromagnetic poles and a mover equipped with independently controllable rotor units comprising windings and permanent magnets, allowing for air gap control and levitation without additional components, thereby reducing friction and simplifying the motor design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the stator comprises windings and/or permanent magnets, then the motor can generate propulsion force, but the cost and weight of the linear stator increase considerably
Solution Approach 1:
The patent extracts the permanent magnets from the stator and relocates them to the mover, while the stator retains only ferromagnetic poles. This extraction reduces the weight and cost of the stationary stator structure, particularly for long trajectories, while the mover with embedded magnets provides the necessary magnetic field interaction for propulsion force generation
Solution Approach 2:
The patent inverts the conventional arrangement by placing permanent magnets in the mover instead of the stator. This inversion allows the stator to be a simpler, lighter ferromagnetic structure while the mover contains the magnetic sources, achieving propulsion through the interaction between mover magnets and stator poles
2Length of stationary object
If the linear stator is made longer for higher elevator shafts, then the motor can cover longer trajectories, but the weight and cost add up considerably
Solution Approach 1:
By extracting permanent magnets from the stator and placing them only in the mover, the patent significantly reduces the weight per unit length of the stator. This makes it feasible to implement long-trajectory applications like high-rise elevators (50m or more) without the weight and cost penalties of conventional long stators with embedded magnets
Solution Approach 2:
The patent uses a simplified ferromagnetic stator structure without expensive permanent magnets, making the stator more cost-effective and lighter. The mover, containing the magnets, becomes the primary magnetic component, enabling long trajectories at reduced overall system cost and weight
3Measurement precision
If additional components are added to control air gap, then the motor control precision improves, but the device complexity increases
Solution Approach 1:
The patent makes the mover serve multiple functions: it provides propulsion force through its permanent magnets and simultaneously generates attraction force toward the stator for air gap control. This multi-functionality eliminates the need for separate air gap control components, reducing device complexity while maintaining control precision
Solution Approach 2:
The patent merges the propulsion function and air gap control function into a single integrated system. The permanent magnets in the mover provide both the propulsive magnetic field interaction with stator poles and the attractive force necessary for maintaining air gap, combining two functions into one component set
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 results in a more cost-effective, efficient, and reliable linear motor with reduced friction losses and improved ride comfort, suitable for high-rise applications like elevators, escalators, and other long movement tracks.
Implementation Method 1
The mover has in each of said counter-faces at least one rotor unit having at least one winding and at least one permanent magnet, which are arranged to co-act with the ferromagnetic poles of the respective side face of the stator beam
Implementation Method 2
The at least one rotor unit comprises at least one winding and at least one permanent magnet
Implementation Method 3
supplying, by means of the at least one drive unit a d-axis current component to the at least one winding of the at least one rotor unit to adjust the length of air gap towards given reference value
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The invention refers to an electric linear motor, control apparatus, transport system and a method. The electric linear motor comprises a longitudinal stator beam (1); at least one mover (24, 26) at least partially surrounding the stator beam (1) and adapted to move along the stator beam (24, 26); which stator beam comprises at least two side faces (6A, 6B; 6C, 6D) located at opposite sides of the stator beam (1), each of the side faces (6A, 6B; 6C, 6D) carrying ferromagnetic poles (8) spaced apart by a pitch (8'), and which mover comprises at least two counter-faces (7A, 7B; 7C, 7D) facing the respective side faces (6A, 6B; 6C, 6D) of the stator beam (1). The mover has in at least one of said counter-faces (7A, 7B; 7C, 7D) rotor units (2, 3, 4, 5) having at least one winding (74, 76) and at least one permanent magnet (71) arranged to co-act with the ferromagnetic poles (8) of the respective side faces (6A, 6B; 6C, 6D) of the stator beam (1). The ferromagnetic stator poles (8) of the stator beam (1) and the rotor units of the mover (24, 26) are used for generating propulsion forces for driving the mover (24, 26) along the stator beam (1) as well as for generating attraction forces to levitate the mover (24, 26) around the stator beam (1) while driving.