Adjustable-Flux PMSM Magnetization for Extended Speed Range
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Solution Overview
Problem
Conventional permanent magnet synchronous machines (PMSMs) face limitations such as fixed speed range, inefficiency in adjusting speed, and susceptibility to demagnetization due to high operating temperatures, which restrict their application and efficiency.
Innovation Solution
The flux-mnemonic permanent magnet synchronous machine (FMPMSM) employs circumferentially magnetized adjustable permanent magnets and flux adjusters, allowing for real-time adjustment of magnetic flux density through current pulses, enabling flexible speed control and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional PM synchronous machine uses fixed permanent magnets, then magnetic structure is simple and reliable, but speed range is limited and back-emf cannot be adjusted
Solution Approach 1:
The patent applies the dynamics principle by making the magnetic flux density adjustable through controllable magnetizing current. The permanent magnets' magnetization state can be dynamically changed by applying current pulses, allowing the machine to adapt its magnetic structure to different operating conditions and extend its speed range beyond conventional fixed-magnet designs.
Solution Approach 2:
The patent changes the magnetic flux density parameter by controlling the magnetization state of permanent magnets through adjustable current. This parameter change enables the machine to operate at extended speed ranges by modifying the back-emf characteristics without changing the physical magnet structure.
2Power
If conventional PM synchronous machine operates at high speed, then power output increases, but back-emf voltage increases proportionally exceeding inverter capacity
Solution Approach 1:
The patent changes the magnetic flux density parameter by controlling the magnetization state of permanent magnets through adjustable current. This parameter change enables the machine to operate at extended speed ranges by modifying the back-emf characteristics without changing the physical magnet structure.
3Reliability
If conventional PM synchronous machine uses materials with low Curie temperature, then manufacturing is easier and cost is lower, but magnets demagnetize at high operating temperatures
Solution Approach 1:
The patent applies preliminary action by pre-magnetizing the permanent magnets to a controlled state before operation. By adjusting the initial magnetization level, the system creates a magnetic buffer that prevents demagnetization at high temperatures, allowing the use of lower-cost materials with lower Curie temperatures while maintaining reliability.
Solution Approach 2:
The patent uses beforehand cushioning by establishing a controlled magnetization state that acts as a protective buffer against thermal demagnetization. The adjustable magnetizing current creates a magnetic reserve that compensates for temperature-induced magnetization loss, protecting the permanent magnets from complete demagnetization during high-temperature operation.
4Speed
If conventional PM synchronous machine adjusts speed beyond nominal speed, then speed range increases, but additional current injection causes increased losses
Solution Approach 1:
The patent changes the magnetic flux density parameter by controlling the magnetization state of permanent magnets through adjustable current. This parameter change enables the machine to operate at extended speed ranges by modifying the back-emf characteristics without changing the physical magnet structure.
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 FMPMSM achieves extended constant power speed range, increased torque flexibility, and enhanced operational efficiency by dynamically adjusting the magnetic flux density, thus overcoming the limitations of conventional PMSMs.
Implementation Method 1
applying at least one current pulse from the inverter to set a magnetic flux linkage between the rotor and stator
Implementation Method 2
at least two circumferentially magnetized permanent magnets, each of the permanent magnets having two poles normal to an air gap between the stator and rotor
Data Source
AI summary
A method of changing a magnetic flux density in an air gap between a stator and a rotor in a real-time flux-mnemonic permanent magnet synchronous machine comprising permanent magnets, the method comprising applying at least one current pulse to adjust a magnetic operating point of the magnets, wherein the at least one current pulse has a duration of less than 3 ms. For applying the at least one current pulses, the method comprises consecutively applying a plurality of primitive pulses.