Electric Vehicle Drive Train Using Multiple Motors
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Solution Overview
Problem
Current electric vehicle drive train architectures are inefficient due to limited torque and power at high speeds, requiring transmissions that add weight, cost, and reliability issues, while existing motor control approaches like VFD technology are insufficient in addressing these limitations.
Innovation Solution
A drive system utilizing electronically controlled, multiple electric motor configurations coupled to an output drive shaft, with an electronic control unit and computer-readable memory, allowing for selective energization and operation in various modes to improve torque and power across a broader speed range without the need for a transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a transmission is incorporated to match motor RPM range with vehicle speed, then torque and power delivery is improved, but device complexity, weight, cost, and reliability deteriorate
Solution Approach 1:
The patent removes the transmission component from the electric vehicle drive train, using multiple electric motors with different gear ratios directly coupled to the drive shaft to eliminate the need for speed conversion, thereby reducing device complexity while maintaining power delivery capability
Solution Approach 2:
The patent divides the single motor function into multiple electric motors, each with different gear ratios, allowing direct coupling to the drive shaft without requiring a transmission system to handle speed conversions
2Power
If a transmission is incorporated to match motor RPM range with vehicle speed, then torque and power delivery is improved, but weight increases
Solution Approach 1:
The transmission system is extracted and removed from the drive train, eliminating its weight contribution to the vehicle while maintaining power delivery through direct motor-to-shaft coupling with multiple motors having different gear ratios
3Power
If a transmission is incorporated to match motor RPM range with vehicle speed, then torque and power delivery is improved, but cost increases
Solution Approach 1:
The transmission component is extracted from the system, eliminating its manufacturing cost while maintaining the ability to deliver appropriate torque and power through multiple motors with different gear ratios directly coupled to the drive shaft
4Power
If a transmission is incorporated to match motor RPM range with vehicle speed, then torque and power delivery is improved, but reliability deteriorates
Solution Approach 1:
The transmission system is extracted and removed from the drive train, eliminating its failure modes and reliability issues while maintaining power delivery capability through multiple electric motors with different gear ratios directly coupled to the drive shaft
5Device complexity
If multiple electric motor configurations are used to eliminate transmission, then device complexity and weight are reduced, but torque and power at high speeds deteriorate
Solution Approach 1:
The drive train is segmented into multiple electric motors, each with different gear ratios, where at least one motor is configured to provide torque and power at high speeds, thereby maintaining high-speed performance while eliminating the transmission system
Solution Approach 2:
The gear ratios of the multiple electric motors are specifically configured with at least one motor having a gear ratio optimized for high-speed operation, changing the mechanical parameters to maintain torque and power delivery at high speeds without requiring a transmission
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 approach enhances performance and efficiency by eliminating the need for a transmission, providing improved torque and power delivery across a wider speed range, reducing weight and cost, and increasing the driving range of electric vehicles.
Implementation Method 1
A drive system for an electric vehicle includes a first electric motor having first stator and rotor portions and a second electric motor having second stator and rotor portions
Data Source
AI summary
An electric vehicle accomplishes speed changes through the use of electronically controlled, multiple electric motor configurations that are coupled to an output drive shaft instead of a speed change transmission. A parallel-coupled motor configuration includes at least two motors that are each coupled to the output drive shaft through respective gear arrangements, each gear arrangement having a respective gear ratio. In a serially-coupled motor configuration, the stator of the second motor is coupled to the rotor of the first motor, where the rotor of the second motor is coupled to the output drive shaft. The required torque to reach or maintain a desired vehicle speed can be obtained by selective energization of either one or both of the motors (in both multi-motor configurations). Two motors are also coupled to a differential gear so that the rotational speed contributed by both motors are additive at the output shaft.