Six-Phase Asynchronous Machine 72 Stator Slots
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Solution Overview
Problem
Asynchronous machines used in electric and hybrid vehicles face limitations in power transmission due to the current-carrying capacity of semiconductor modules, which restricts the achievable torque and power output, especially when operating in multiple phases.
Innovation Solution
A six-phase asynchronous machine design with a total of 72 stator slots, optimized geometry ratios between stator yoke height and slots, and rotor slots, and a configuration of two three-phase systems phase-shifted by 30 degrees, which increases torque and power while minimizing parasitic effects like noise and torque fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of phases is increased from three to six to double the power output, then the power and torque are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The six-phase asynchronous machine is segmented into two independent three-phase systems, each with its own inverter and control. This segmentation allows the complex six-phase system to be managed as two simpler three-phase systems, reducing control complexity while maintaining the power-doubling benefit. The stator is also segmented with 72 slots arranged to accommodate both three-phase systems with 30-degree phase shift.
Solution Approach 2:
The six-phase asynchronous machine design enables a single motor unit to perform multiple functions: it can operate as a six-phase motor for maximum power output, or be controlled as two independent three-phase motors for reduced complexity applications. The 72-stator-slot configuration is universally optimized to work with both three-phase and six-phase winding arrangements, providing multi-functionality.
2Power
If the stator yoke height is increased to handle higher currents and power, then the power transmission capacity is improved, but the weight and volume increase
Solution Approach 1:
The patent optimizes the stator yoke height parameter to a specific range (3.5-4.5 mm per stator hole) that provides the necessary mechanical strength and magnetic flux path capacity for six-phase operation without excessive weight. This parameter change allows the stator to handle higher six-phase currents while maintaining acceptable weight, achieving a balance between power transmission capacity and mass.
3Power
If the number of stator slots is increased to 72 for optimal six-phase winding distribution, then the torque and power are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The 72 stator slots are not uniformly distributed but are arranged with specific local characteristics to accommodate the two three-phase systems with 30-degree phase shift. The slot distribution pattern is optimized locally in different circumferential zones to achieve optimal winding factors and minimize harmonics, while maintaining manufacturability through standardized slot dimensions and spacing.
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 design enhances torque and power output while reducing parasitic effects, allowing for a smaller stator dimension and lower weight, and achieving higher overall speed with minimized electromagnetic noise and torque fluctuations.
Implementation Method 1
Alternating currents are induced in the conductive cage by the rotating magnetic field. Torque is created by the interaction of the rotating magnetic field of the stator and the magnetic field induced in the rotor.
Data Source
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AI summary
For an asynchronous machine (1), in particular for use in electric vehicles or hybrid vehicles, comprising a rotor (10) and a stator (20) which surrounds the rotor (10), wherein an external stator yoke (21) with a stator yoke height (h21) is formed on the stator (20) and a large number of radially inwardly projecting stator teeth (22) of the same length are formed on the stator yoke (21), wherein a stator slot (23) is respectively formed between adjacent stator teeth (22), wherein an internal rotor yoke (11) is formed on the rotor (10) and a large number of radially outwardly projecting rotor teeth (12) of the same length are formed by the rotor yoke (11), wherein a rotor slot (13) is respectively formed between adjacent rotor teeth (12), wherein the asynchronous machine is of six-phase design, it is proposed that a total number (N1) of stator slots, which denotes the total number of stator slots (23) formed on the stator (20), is seventy-two.