Stator Cooling Slot Layout for Compact Fractional-Winding Motors
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Solution Overview
Problem
Conventional fractional-slot-winding motors face challenges with high bulkiness, complex windings, and high component count, leading to reduced torque density and increased manufacturing costs.
Innovation Solution
The design incorporates multiple sets of fluidic pathways, including fluid-passage slots, first-fluid-recirculating slots, and second-fluid-recirculating slots, which allow coolant to enter and exit from the same side of the stator, enhancing cooling efficiency and reducing winding extensions by minimizing the number of connections among coil units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fractional-slot-winding motors use complex windings to achieve high torque density, then torque density increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The motor is divided into modular components: a stator with standardized slots, a rotor with standardized poles, and pre-assembled coil units. Each coil unit is a discrete module that can be independently manufactured and then assembled into the motor, breaking down the complex winding process into manageable segments.
Solution Approach 2:
Coil units are pre-assembled with their magnets and windings before being installed in the motor. This preliminary preparation allows for standardized manufacturing of coil units that can be easily inserted into the stator slots, reducing on-site assembly complexity and enabling the use of complex fractional-slot windings without proportionally increasing overall manufacturing difficulty.
2Adaptability or versatility
If fractional-slot-winding motors use many unique components to form complex windings, then winding flexibility improves, but ease of manufacture deteriorates
Solution Approach 1:
The motor design uses universal standardized components: all coil units have the same basic structure, all stator slots are identical in form, and all rotor poles follow a standard pattern. These universal components can be adapted to create different winding configurations by changing how they are assembled together, providing winding flexibility without requiring unique components for each configuration.
Solution Approach 2:
The design achieves different winding configurations by changing parameters such as the number of coil units per slot, the arrangement pattern of coils, and the magnetic pole configurations, rather than creating fundamentally different component types. This allows flexible winding designs while maintaining standardized manufacturing processes for the base components.
3Volume of moving object
If winding extensions are minimized to reduce motor size, then volume decreases, but ease of operation deteriorates
Solution Approach 1:
The coil units are designed to extend primarily in the radial dimension rather than axially, with the majority of the winding length contained within the stator slot depth. This dimensional reorganization allows compact axial length and reduced overall motor volume while maintaining adequate space for coil connections through the radial and circumferential dimensions.
Solution Approach 2:
The coil windings are nested within the stator slots, with multiple turns of wire contained within the slot depth. This nesting arrangement accommodates the necessary winding extensions and connection lengths within the confined space of the slot, reducing the overall motor volume while preserving the functionality required for ease of coil connection and assembly.
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 increases torque density, reduces motor size, and simplifies manufacturing by minimizing winding complexities and component count, while maintaining high efficiency and reducing cogging torque.
Implementation Method 1
The cooling fluid can pass through the stator using these slots
Implementation Method 2
The plurality of first-fluid-recirculating slots and the plurality of second-fluid-recirculating slots extend to and open only at one of the coil-interconnection side or the bus-bar side
Data Source
AI summary
Described herein are electric motors with stators comprising multiple sets of fluidic pathways, e.g., a plurality of fluid-passage slots, a plurality of first-fluid-recirculating slots, and a plurality of second-fluid-recirculating slots. The plurality of fluid-passage slots extends through the stator parallel to the primary axis between the coil-interconnection side and the bus-bar side and circumferentially offset from each other. The cooling fluid can pass through the stator using these slots. The plurality of first-fluid-recirculating slots and the plurality of second-fluid-recirculating slots extend to and open only at one of the coil-interconnection side or the bus-bar side. Furthermore, each of the plurality of first-fluid-recirculating slots is fluidically coupled to one of the plurality of second-fluid-recirculating slots. As such, the cooling fluid enters and leaves these recirculating slots from the same side of the stator. Overall, the stator cooling may be also used to redistribute the cooling fluid within a drive unit.