Rotor Magnetization Control in Compressor Drive Assembly
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Solution Overview
Problem
Conventional methods for manufacturing electrical rotating machines face challenges such as assembly difficulties due to magnetic forces, increased risk of rotor/stator damage, and non-optimal performance in turbomachines like turbochargers, leading to no-load losses and high manufacturing costs.
Innovation Solution
A drive system with an inverter and control device that uses modulatable magnetization of rotor elements, allowing for controlled magnetization and demagnetization through the stator windings, eliminating the need for additional structures and reducing no-load losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If permanent magnets are attached to the rotor body during assembly, then the rotating machine can generate magnetic field for operation, but assembly difficulties occur due to magnetic forces and increased risk of rotor/stator shocks
Solution Approach 1:
The patent applies preliminary action by magnetizing the magnetic elements after assembly rather than before. The rotor is first assembled with non-magnetized magnetic elements, avoiding assembly difficulties. After assembly, a dedicated magnetization process is performed to magnetize the elements, thus achieving the magnetic field generation function without compromising the ease of manufacture.
2Reliability
If a dedicated magnetization structure is added to magnetize rotor elements, then magnetization can be achieved, but the size and manufacturing cost of the rotating machine increase
Solution Approach 1:
The patent applies universality by making the stator windings serve dual functions: they generate the magnetic field for motor operation and also serve as the magnetization means during the magnetization process. This eliminates the need for a separate dedicated magnetization structure, thereby reducing device complexity and manufacturing cost while maintaining the capability to magnetize rotor elements.
3Power
If the rotating machine operates with permanent magnetization, then it can drive the turbomachine, but no-load losses occur during idle periods when the machine is not powered
Solution Approach 1:
The patent applies dynamics by making the magnetization of the rotor elements controllable and modifiable. Instead of permanent fixed magnetization, the magnetic elements can be demagnetized or have their magnetization reduced during idle periods by controlling the stator windings to generate a demagnetizing field. This dynamic control of magnetization allows the machine to maintain driving capability when needed while minimizing no-load losses during idle periods.
4Ease of manufacture
If magnetic elements are used in the rotor, then assembly is simplified compared to pre-magnetized magnets, but additional structure is needed for magnetization
Solution Approach 1:
The patent resolves this contradiction by making the stator windings universal: they perform both the function of generating operational magnetic field and the function of magnetizing the rotor elements. This eliminates the need for additional dedicated magnetization structure, thereby maintaining the assembly simplicity advantage of using non-magnetized magnetic elements while avoiding the complexity increase that would otherwise result from adding separate magnetization equipment.
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 system simplifies assembly, reduces manufacturing costs, and minimizes no-load losses by modulating the magnetic field based on operational conditions, enhancing performance in turbomachines.
Implementation Method 1
a magnetic field is generated in the cavity, by means of dedicated windings mounted in the stator, to magnetize the magnetic elements of the rotor
Implementation Method 2
the inverter is controlled so that the magnetic field intended to magnetize the magnetic elements is generated by the stator windings which are usually used to set the rotor in motion
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a drive system (2) comprising: - an inverter (6) comprising a first input (14), a second input (16) and N outputs (18); - a rotating machine (8) comprising a stator, the windings of which are connected at the output to a common point (44), and a rotor (32) comprising at least one magnetic element (48) made of a material with adjustable magnetisation; - an output switching element (10) connected between the common point (44) and the second input (16); and - a control device (12) configured to, simultaneously, during a magnetising step: • control the output switching element (10) so that it is in an on state for a predetermined magnetisation time interval; and • control the inverter (6) to, during the magnetisation time interval, connect the first input (14) to at least one and at most N-1 output(s) (18).