Multi-Motor Drive Unit Layout for Lower Cruising Stator Losses
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Solution Overview
Problem
Existing electric drive systems face challenges such as complex manufacturing, stator losses during cruising, and inefficient use of space due to twin motor architectures, particularly in vehicles with planetary gear sets and dual motor configurations.
Innovation Solution
An electric drive unit with multiple sets of electric motors and summation gear sets, featuring disconnect clutches and independent inverter control, allows for efficient operation during partial loads by disconnecting motors and optimizing space usage through compact design and cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two comparatively large diameter and short axial length electric motors are used, then the electric drive can provide sufficient power, but stator losses increase during vehicle cruising
Solution Approach 1:
The patent divides the motor system into multiple smaller motor units (first and second motor units with respective rotors and stators) that can operate independently or in combination. This segmentation allows the system to use only the necessary motor capacity during partial load conditions, reducing stator losses while maintaining sufficient power output when needed.
2Adaptability or versatility
If a Ravigneaux gear set is used in a multi-motor electric drive, then power distribution is achieved, but the gear set complexity increases manufacturing difficulty
Solution Approach 1:
Instead of using a complex Ravigneaux gear set, the patent segments the power transmission system into separate summation gear sets (first and second summation gear sets) for each motor unit. This simplification maintains the power distribution capability while significantly reducing manufacturing complexity and improving ease of production.
3Loss of energy
If disconnect clutches are added to allow motor disconnection during partial load, then operating efficiency increases, but device complexity increases
Solution Approach 1:
The disconnect clutches are pre-configured in the system to enable rapid engagement and disengagement of motor units. This preliminary preparation allows the control system to quickly connect or disconnect specific motor units based on load conditions, achieving high operating efficiency without requiring complex real-time mechanical reconfiguration.
4Power
If twin motor electric axle architecture is used, then power delivery is improved, but unused volume in the center reduces compactness
Solution Approach 1:
The patent arranges the motor units and summation gear sets in a distributed configuration around the axial center rather than concentrating components in the center. This dimensional redistribution eliminates unused central volume while maintaining the power delivery capability of twin motor architecture, thereby improving compactness.
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 reduces stator iron losses, increases operating efficiency, and enhances space efficiency by allowing independent motor operation and integration of cooling systems, particularly during vehicle coasting conditions.
Implementation Method 1
a first set of rotors, each rotor configured to electromagnetically interact with the first 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 in which each rotor is configured to electromagnetically interact with the first set of stator windings and rotationally couple to a distinct gear in a first summation gear set, a second set of rotors in which each rotor is 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 disconnect clutch configured to rotationally disconnect a first rotor in the first set of rotors from the first summation gear set.