Multi-Motor Electric Drive Unit With Split Gearsets for Lower Stator Loss
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Solution Overview
Problem
Existing electric drive systems face challenges such as complex manufacturing, high costs, and inefficient use of space due to the use of single large motors and complex gear sets like Ravigneaux, leading to stator losses and unused motor volumes.
Innovation Solution
The electric drive unit employs multiple smaller electric motors with independent inverters, each coupled to distinct summation gear sets, allowing for independent speed control and reducing component sizes, thereby improving manufacturing efficiency and space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single large traction motor is used, then the drive unit can achieve required power output, but stator losses increase during vehicle cruising
Solution Approach 1:
The single large traction motor is divided into multiple smaller motors (e.g., two or more motors per axle). Each motor operates independently with its own inverter, allowing selective operation during cruising to minimize stator losses while maintaining required power output through parallel operation when full power is needed.
2Power
If two comparatively large diameter and short axial length electric motors are used, then power output is achieved, but unused volume remains in the center of the motors impacting compactness
Solution Approach 1:
The motor configuration is segmented into multiple smaller diameter motors arranged to eliminate unused central volume. This allows better space utilization in the drive unit while maintaining the required power output through combined motor capability.
3Adaptability or versatility
If a Ravigneaux gear set is used, then multiple motor inputs can be summed, but the gear set becomes complex and difficult to manufacture
Solution Approach 1:
The complex Ravigneaux gear set is segmented into multiple simpler summation gear sets (e.g., two separate planetary gear sets). Each summation gear set handles a subset of motor inputs, reducing the complexity and manufacturing difficulty of each individual gear set while maintaining the capability to sum multiple motor inputs through parallel configuration.
4Ease of manufacture
If multiple motors with independent inverters are used, then manufacturing costs decrease via economies of scale, but device complexity increases
Solution Approach 1:
The drive unit is segmented into multiple independent motor-inverter-gearset modules. Each module can be manufactured separately using standardized components and processes, achieving economies of scale. The modular architecture manages system complexity through clear functional separation and independent control of each module.
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 enhances drive unit longevity, reduces manufacturing costs, and increases space efficiency, enabling the drive unit to be packaged in various vehicle platforms while minimizing stator losses and improving operating efficiency.
Implementation Method 1
a first set of rotors each configured to electromagnetically interact with the first set of stator windings; a second set of rotors configured to electromagnetically interact with the second set of stator windings
Data Source
AI summary
Methods and systems for an electric drive unit. The electric drive unit includes, in one example, a stator assembly with a first set of stator windings and a second set of stator windings, a first set of rotors each configured to electromagnetically interact with the first set of stator windings and rotationally couple to a distinct gear in a first summation gear set. The electric drive unit further includes a second set of rotors configured to electromagnetically interact with the second set of stator windings and rotationally couple to a distinct gear in a second summation gear set. The electric drive unit further includes a first inverter and a second inverter both electrically coupled to the stator assembly and in the drive unit the first inverter and the second inverter are configured to independently control speeds of the first set of rotors and the second set of rotors, respectively.