Six-Phase PM Machine Layout for Reduced Mutual Inductance
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Solution Overview
Problem
Six-phase electric machines experience unwanted mutual inductance interaction due to interference, which affects their performance, particularly in medium-duty and heavy-duty applications, and existing technologies have not adequately addressed this issue without compromising fundamental performance.
Innovation Solution
A six-phase electric machine design featuring a stator and rotor configured as two coupled three-phase electric machines with a fractional slot combination and concentrated windings, along with mechanical separation of at least 60 mechanical degrees and V-shaped magnets segmented axially, reduces mutual inductance interaction and torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If six-phase electric machines use conventional winding configurations with coils in close proximity, then the machine can achieve high power density and compact size, but unwanted mutual inductance interaction occurs due to magnetic field interference between phases
Solution Approach 1:
The six-phase machine is segmented into two independent three-phase machines that are mechanically separated by at least 60 mechanical degrees. This segmentation isolates the magnetic fields of the two three-phase systems, reducing mutual inductance interaction between phases while maintaining the high power density benefits of the six-phase configuration.
Solution Approach 2:
The patent introduces mechanical angular separation in the spatial dimension between the two three-phase machines. By positioning the machines at least 60 mechanical degrees apart, the magnetic field interference is reduced in the angular dimension while maintaining compact overall machine dimensions.
2Object-affected harmful factors
If mechanical separation between phases is increased to reduce mutual inductance interaction, then phase interference is reduced, but the machine size and volume increase
Solution Approach 1:
By segmenting the six-phase machine into two independent three-phase machines with concentrated windings, the patent achieves effective magnetic field isolation with minimal mechanical separation (at least 60 mechanical degrees). This segmentation allows compact positioning while still reducing mutual inductance interaction.
Solution Approach 2:
The patent changes the winding configuration parameter from conventional distributed windings to concentrated windings, and introduces a specific mechanical separation parameter (at least 60 mechanical degrees). These parameter changes achieve phase interference reduction without proportionally increasing machine volume.
3Ease of manufacture
If conventional three-phase machine configurations are used, then the design is simple and easy to manufacture, but fault tolerance is limited and torque ripple is higher
Solution Approach 1:
The six-phase machine with two independent three-phase systems provides multi-functionality: it maintains the simplicity and manufacturability of conventional three-phase machines while simultaneously achieving enhanced fault tolerance. If one three-phase system fails, the other can continue to operate, providing backup functionality.
Solution Approach 2:
By changing the phase number from three to six and introducing mechanical separation, the patent achieves improved fault tolerance and reduced torque ripple while maintaining design simplicity through the use of standard concentrated winding techniques and conventional magnet configurations.
4Manufacturing precision
If distributed windings are used in six-phase machines, then the winding factor is lower and harmonic distortion is higher, but the manufacturing process is more conventional and established
Solution Approach 1:
By segmenting the machine into two three-phase systems with concentrated windings, the patent achieves high winding factors (at least 95%) and low harmonic distortion (less than 50%). The concentrated winding configuration within each three-phase system is simpler and more conventional to manufacture than distributed windings.
Solution Approach 2:
Instead of using distributed windings and accepting lower winding factors, the patent inverts the approach by using concentrated windings with mechanical separation to achieve both high winding factors and ease of manufacture. This inversion of the conventional approach resolves the contradiction between manufacturing precision and conventionality.
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 solution effectively reduces mutual inductance interaction and torque ripple, enhances winding factor, and improves fault tolerance, resulting in improved performance and reduced noise, vibration, and harshness issues, while maintaining high power ratings suitable for medium-duty and heavy-duty applications.
Implementation Method 1
permanent magnet machines such as motors and generators use two coils of wire brought into close proximity with each other so as to link the magnetic field from one coil to another magnetic field from the other coil, generating voltage in the second coil as a result
Implementation Method 2
link the magnetic field from one coil to another magnetic field from the other coil
Implementation Method 3
the rotor includes a plurality of V-shaped magnets
Data Source
AI summary
Six-phase permanent magnet-type electric machines are disclosed. The electric machine includes a stator and a rotor configured to operate as a first three-phase electric machine and a second three-phase electric machine. The first and second three-phase electric machines are coupled with each other via a fractional slot combination with concentrated windings such that a mechanical separation between the first and second three-phase electric machines is at least 60 mechanical degrees.