Pulse-Magnetized PMSM Flux Control for Back-EMF and Speed Range
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Solution Overview
Problem
Conventional PM synchronous machines face limitations in adjusting back-emf voltage, speed range, and efficiency due to fixed magnetic structures and material demagnetization at high temperatures, necessitating mechanical transmissions and additional current injection, which are inefficient and costly.
Innovation Solution
A flux-mnemonic permanent magnet synchronous machine (FMPMSM) with adjustable permanent magnets and flux adjusters, controlled by a power inverter and microcontroller, allows real-time adjustment of magnetic flux linkage through current pulses, enabling flexible speed range and efficiency optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional PM synchronous machines use fixed permanent magnets, then the machine structure is simple and reliable, but the back-emf voltage cannot be adjusted and the speed range is limited
Solution Approach 1:
The patent applies the dynamics principle by making the magnetic structure adjustable rather than fixed. The permanent magnets can be repositioned or reconfigured to change the number of active poles, enabling dynamic adjustment of back-emf voltage and speed range. This transforms a static magnetic structure into a dynamic one that can adapt to different operating conditions.
Solution Approach 2:
The patent applies segmentation by dividing the magnetic structure into separable permanent magnets that can be independently positioned or configured. This allows the number of active poles to be changed by reconfiguring the segmented magnet arrangements, providing adaptability while maintaining structural simplicity.
2Power
If conventional PM synchronous machines operate at high speeds, then the power output increases, but the back-emf voltage increases proportionally exceeding insulation and inverter limits
Solution Approach 1:
The patent uses dynamics to enable real-time adjustment of the magnetic flux linkage by reconfiguring the permanent magnets. This allows the back-emf voltage to be dynamically controlled to match the inverter's voltage capacity, preventing excessive voltage that would exceed insulation and inverter limits while maintaining high-speed operation.
3Ease of manufacture
If conventional PM synchronous machines use materials with low Curie temperature, then the manufacturing cost is reduced, but the permanent magnets demagnetize at higher operating temperatures
Solution Approach 1:
The patent applies preliminary action by pre-configuring the permanent magnets with appropriate thermal margins and positioning them to optimize flux distribution. This preliminary design consideration ensures that even materials with lower Curie temperatures can operate reliably at elevated temperatures without demagnetization, balancing manufacturing cost with thermal reliability.
4Speed
If conventional PM synchronous machines adjust speed beyond nominal speed, then the speed range expands, but additional current injection is required causing increased losses
Solution Approach 1:
The patent applies dynamics by enabling speed adjustment through permanent magnet reconfiguration rather than additional current injection. This dynamic structural adjustment allows the machine to operate beyond nominal speed by changing the effective pole count, expanding the speed range without the energy losses associated with continuous current injection.
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 efficient power output by dynamically altering magnetic flux density and back-emf, expanding the speed range and torque capabilities without mechanical complexity, using soft magnetic materials and reduced power consumption.
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.