Motor Driving Device Reducing Magnetic Bearing Load
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Solution Overview
Problem
Conventional chiller systems face challenges in reducing the levitation force required for initial alignment of rotor and stator, leading to increased size and manufacturing costs of magnetic bearings, and variability in levitation force due to arbitrary stator tooth arrangements, which affects motor control reliability.
Innovation Solution
Applying a greater current to the coil farthest from the ground among multiple coils to reduce the levitation force needed for initial alignment, and generating additional levitation force through magnetic bearings after current application, while uniformly disposing teeth in the stator to enhance motor control reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic bearings are designed to generate greater levitation force for initial alignment, then the rotor can be reliably levitated, but the size and manufacturing cost of the magnetic bearings increase
Solution Approach 1:
The patent applies a preliminary alignment force through the coil assembly before the magnetic bearing operates. By pre-positioning the rotor using the coil-generated magnetic field, the magnetic bearing only needs to maintain this position rather than generate the full levitation force from scratch, thereby reducing its required size and complexity while ensuring reliable initial alignment
2Reliability
If magnetic bearings are designed to generate greater levitation force, then the rotor can be reliably levitated, but the manufacturing cost increases
Solution Approach 1:
The coil assembly provides a preliminary alignment function that reduces the performance requirements for the magnetic bearing. This division of functionality allows the magnetic bearing to be manufactured at a lower cost while still achieving reliable initial alignment through the combined action of the coil and magnetic bearing
3Ease of manufacture
If stator teeth are arbitrarily arranged, then manufacturing is simplified, but the levitation force magnitude varies and motor control reliability decreases
Solution Approach 1:
The patent changes the arrangement parameter of the stator teeth from arbitrary to uniformly distributed positions. This parameter change ensures that the magnetic field generated by the coil assembly acts symmetrically on the rotor, providing consistent levitation force magnitude and direction, thereby improving motor control reliability while maintaining manufacturing feasibility
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 reduces the magnitude and cost of magnetic bearings, decreases the overall size of the motor, and enhances motor control reliability by allowing for symmetrical tooth positioning, thereby reducing the load on magnetic bearings and improving alignment efficiency.
Implementation Method 1
a first coil C1... generates a magnetic force by applying a current, and thus the rotor 120 is levitated upward
Implementation Method 2
magnetic bearings (130, 135) configured to generate a magnetic force which levitates the rotating shaft upward
Implementation Method 3
a rotor (120) disposed in the stator and rotating due to a magnetic field generated in the plurality of coils
Data Source
AI summary
A motor driving device which can reduce a load burden on a rotating shaft when a magnetic bearing is initially operated. When a rotor and a stator are initially aligned, the motor driving device can apply a greater current to a coil positioned farthest away from the ground among a plurality of coils than to the other coils, so as to reduce a levitation force necessary for initial alignment of the rotor and the stator.