Reluctance Motor Phase Overlap Control for Noise Reduction
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Solution Overview
Problem
Switched reluctance motors experience noise issues and rotor instability, particularly at low speeds, leading to uneven running and potential stopping, which existing control methods fail to adequately address.
Innovation Solution
The method involves gently decelerating the rotor by maintaining phase overlap until energization time expires, evaluating rotor position via sensors, and adjusting the switch-on time for the second phase to create a quasi-random energization pattern, dividing the rotor step into phases with only one phase energized before and both phases energized after a specific position, and implementing a minimum current to prevent jerky movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotor is controlled using conventional switching methods, then the motor can operate at high speeds, but noise issues and rotor instability occur at low speeds
Solution Approach 1:
The patent implements dynamic control of phase switching timing based on real-time rotor position feedback. The switch-on position for the second phase is adjusted dynamically rather than being fixed, allowing the system to adapt to varying load conditions and rotor speeds. This dynamic adjustment enables the motor to maintain stable operation across a wide speed range while minimizing noise and vibration at low speeds.
Solution Approach 2:
The patent employs sensor-based rotor position detection to provide feedback for controlling the switching timing of phase excitations. The actual rotor position is continuously monitored and used to determine the optimal switch-on moment for the second phase, creating a closed-loop control system that eliminates the acoustic tones and instability associated with open-loop conventional switching methods.
2Object-affected harmful factors
If phase switching is optimized for smooth operation, then noise is reduced, but rotor position precision and control accuracy may be compromised
Solution Approach 1:
The patent determines the switch-on position for the second phase in advance based on the desired rotor position and maintains this timing relationship throughout operation. By pre-calculating and maintaining a specific angular offset (approximately 7.5 degrees before the aligned position) between rotor position and phase switch-on timing, the system achieves both noise reduction through consistent phase overlap and precise rotor position control.
3Use of energy by moving object
If the motor operates at very low speeds, then energy efficiency improves, but the rotor exhibits jerky movement and instability
Solution Approach 1:
The patent changes the switching parameters (phase overlap duration and switch-on timing) as a function of rotor speed and load conditions. At very low speeds, the extended phase overlap and adjusted timing create a slightly sluggish but stable rotor rotation characteristic that prevents jerky movement while maintaining energy efficiency. The system adapts its control parameters to match the operational requirements at different speed ranges.
4Ease of operation
If the switch-on time for the second phase is fixed, then control simplicity is maintained, but acoustic tones and rotor instability occur
Solution Approach 1:
The patent enables the control system to automatically adjust the second phase switch-on timing based on real-time rotor position feedback without requiring complex external intervention. The sensor system and control algorithm work together to self-regulate the phase switching moments, eliminating acoustic tones and instability while maintaining operational simplicity through automated adaptation to load and speed variations.
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 significantly reduces noise, prevents jamming and damage to food during low-speed operations, and allows for smooth operation of reluctance motors in kitchen appliances by ensuring continuous movement without crushing, while maintaining adaptability to load changes and high-speed capabilities.
Implementation Method 1
the first coil is already excited... additionally exciting the coil that follows in the direction of rotation of the rotor
Implementation Method 2
the torque, particularly at low speeds, can be so small that the rotor stops... the position of the rotor in relation to the stator field
Implementation Method 3
An evaluation of the rotor position that has been reached is then carried out via a sensor system
Data Source
Figure 1
AI summary
The invention relates to a method for controlling a reluctance motor which comprises a rotor and a stator. The rotor comprises a plurality of rotor segments and the stator comprises a number which are independent from the coils, for example, six rotor segments for eight coils. The invention also relates to a control device which applies tension to a coil of a respective phase of the stator. According to the invention, at the moment when a first coil is excited, i.e. when a rotor segment is displaced towards the coil, the second coil which follows in the rotational direction of the rotor, can also be excited, and the position of the rotor is detected by sensors. The aim of the invention is to produce a method, wherein a reluctance motor can be controlled in an improved manner when running at a very high rotational speed and also when running at a very low rotational speed. According to the invention, the first coil is excited according to a predetermined, modifiable time frame and the subsequent coil is excited in the form of phase overlapping, within a time frame under the proviso that the position of the rotor is determined. Phase overlapping is maintained until the expiration of the time frame.