Synchronous Permanent Magnet Machine Independent Stator Pole Pairs
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Solution Overview
Problem
Existing rotating electric machines face challenges in achieving high efficiency and power density while maintaining manufacturability, particularly in large diameter and low speed applications, where the design and construction of generators need improvement to cope with increasing power and efficiency requirements.
Innovation Solution
A rotating electric machine design featuring a rotor with magnets distributed along its circumference and a stator with independently defined stator pole pairs and slots, where the number of stator slots is connected to the number of rotor magnets and pole pairs through the equation Ns=Nr±2ps, allowing for improved manufacturability and reduced magnetic flux path length, thereby enhancing efficiency and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of stator pole pairs is made dependent on the number of rotor pole pairs (conventional design), then the magnetic flux path is optimized for traditional machines, but the manufacturability of stator coils and stator yoke deteriorates and power density is limited
Solution Approach 1:
The invention segments the relationship between stator and rotor pole pairs by making them independent variables. The stator is divided into Ns slots that can be independently configured from the rotor's Nr magnets, allowing separate optimization of stator manufacturability and rotor performance without coupled constraints
Solution Approach 2:
The invention changes the fundamental parameter relationship from dependent (conventional) to independent (novel). By defining the stator pole pairs ps independently from rotor pole pairs pr, the design allows optimization of stator manufacturability parameters without being constrained by rotor magnet configuration
2Power
If large diameter and low speed design is used to increase power output, then the power output increases, but the efficiency and power density fail to meet increasing requirements
Solution Approach 1:
The invention changes the design parameters by allowing independent optimization of stator slots Ns and rotor magnets Nr. This enables achieving high power output through optimized magnetic coupling without the losses associated with conventional large-diameter low-speed designs
Solution Approach 2:
The invention employs advanced magnetic materials in the rotor magnets to achieve high power density. The independent pole pair design allows optimal utilization of these advanced materials to maximize power output while minimizing energy losses
3Power
If conventional rotor-stator pole pairing is used, then the magnetic flux path is traditional, but all magnets do not contribute equally to torque and iron losses are higher
Solution Approach 1:
The invention applies local quality optimization by configuring stator slots Ns= Nr±2ps to create specific local magnetic flux distributions. This ensures that each rotor magnet Nr has optimal local coupling with stator teeth, maximizing torque contribution and minimizing local iron losses in the stator yoke
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 design results in higher efficiency, increased power density, reduced radial forces on stator teeth, and simplified stator coil manufacturing, with all magnets contributing to torque and reduced iron losses, leading to improved mechanical handling and reduced material costs.
Implementation Method 1
Permanent magnet (PM) generators are typically characterized by the following advantages: simple construction, high efficiency, high power factor and high power density
Implementation Method 2
The transversal-oriented magnet configuration is characterized by a partially non-magnetic rotor core with alternating transversal-oriented permanent magnets and pole pieces to concentrate the flux and direct it radially toward the stator teeth
Data Source
AI summary
A rotating electric machine, especially synchronous permanent magnet machine, is provided. The machine includes a rotor with a given number of magnets distributed along the circumference and a given number of rotor pole pairs, and further comprising a stator with a given number of stator pole pairs and a given number of stator slots. The efficiency and the power of the machine are improved by making the number of stator pole pairs independent of the number of rotor pole pairs.