Variable Reluctance Actuator Torque Profile
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Solution Overview
Problem
Existing rotary actuators for switchgears and contactors require complex and costly systems to provide constant torque in multiple directions over a large angular range, making them inefficient and expensive for applications needing torque in a unique direction within a limited angular span.
Innovation Solution
A single-phase variable-reluctance rotary actuator with a radial-flux structure featuring a single coil and eccentric salient poles, allowing for a variable air gap and torque profile tailored to the specific angular position, reducing manufacturing and implementation costs with a simple electronic control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a common rotary motor is used to provide constant torque at any angular position, then the actuator can operate over a large angular range, but the device complexity and cost increase due to complex electronic drive requirements
Solution Approach 1:
The actuator divides the rotational movement into discrete angular positions using multiple detents on the rotor, each corresponding to a specific switching position. This segmentation allows the actuator to operate over a limited angular range with simple control logic, eliminating the need for complex electronic drives while maintaining adaptability for switching applications.
Solution Approach 2:
The actuator employs variable reluctance characteristics that change dynamically with rotor position, creating position-dependent torque. This dynamic behavior allows the system to provide sufficient torque only at the required angular positions within a limited range, reducing the need for complex control systems while maintaining operational versatility.
2Force
If a rotary motor with complex electronic drive is used, then constant torque can be provided at any angular position, but the manufacturing and implementation costs increase
Solution Approach 1:
The actuator uses the motor's own inductance variations with rotor position to generate the necessary torque characteristics. The position-dependent inductance creates natural torque pulses that drive the rotor to specific detent positions, eliminating the need for complex external control electronics and reducing manufacturing costs while maintaining torque consistency at required positions.
Solution Approach 2:
The actuator exploits changes in magnetic reluctance parameters as the rotor moves through different positions. By designing the stator and rotor geometries to create specific reluctance variations, the system generates position-dependent torque without complex electronics, reducing manufacturing costs while providing sufficient torque consistency for switching applications.
3Ease of manufacture
If a single-phase variable-reluctance structure is used, then the manufacturing cost is reduced, but the torque profile must be tailored to specific angular positions
Solution Approach 1:
The actuator uses asymmetric stator and rotor pole geometries to create position-dependent magnetic reluctance. This asymmetry generates a unique torque profile that provides sufficient torque only at the required switching positions within a limited angular range. The asymmetric design simplifies manufacturing compared to symmetric multi-phase motors while providing tailored torque characteristics for specific applications.
Solution Approach 2:
The actuator design pre-configures the magnetic circuit geometry to generate torque pulses at specific angular positions before actuation occurs. The stator and rotor pole shapes are designed in advance to create the desired torque profile, eliminating the need for complex real-time control and allowing cost-effective manufacturing with tailored torque characteristics for predetermined switching positions.
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 actuator provides efficient unidirectional torque within a limited angular span, optimizing cost and reliability by using inexpensive materials and a straightforward control system, while allowing for tailored torque profiles and reduced energy losses.
Implementation Method 1
single-phase variable-reluctance radial-flux structure
Implementation Method 2
single coil and eccentric salient poles
Data Source
Figure 1a~2
Figure 3~4
Figure 5
AI summary
A variable reluctance actuator (1) comprises: - a stator having a stator core (2) comprising a single stator salient pole (7) with a single coil winding (4); - a rotor having a rotor core (3) rotatable around an axis of rotation (R) between a start position and an end position and comprising a single rotor salient pole (8); - a shaft (6) integrally rotatable with the rotor core (2), wherein an air gap (9) is formed between the rotor salient pole (8) and the stator salient pole (7) when the rotor core (3) moves between the start and the end positions, the stator salient pole (7) and the rotor salient pole (8) being shaped such that the radial distance between a same point on the rotor salient pole (8) and the stator salient pole (7) at the air gap (9) varies as a function of the angular position of the rotor core (3).