Dual-Motor Planetary Drivetrain With Infinitely Variable EV Drive
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Solution Overview
Problem
Conventional electric drivetrains are constrained by a fixed motor speed for a given road speed, limiting the optimization of efficiency, constant torque operation, and regenerative power capacity, which existing solutions such as multi-mode gearboxes and dual motors on a common axis are unable to fully address.
Innovation Solution
A method involving a dual motor setup where one motor operates in torque control mode and the other in speed control mode, both coupled to a planetary gear set on opposite sides of an output node, allowing for decoupling of motor speed from vehicle speed and enabling pseudo mechanical points for high efficiency operation, including single motor mode with torque multiplication and infinitely variable transmission capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional electric drivetrain with fixed motor speed for given road speed is used, then the structure is simple, but the optimization of efficiency, constant torque operation, and regenerative power capacity is limited
Solution Approach 1:
The drivetrain is segmented into two independent motor units (first motor unit and second motor unit), each capable of independent operation. This segmentation allows each motor to operate independently to optimize efficiency while providing the necessary torque and power to the wheels, thereby resolving the contradiction between structural simplicity and efficiency optimization capability.
Solution Approach 2:
Each motor unit is designed with multi-functionality, capable of operating in multiple modes including torque control mode and speed control mode. The motors can independently provide propulsion, enable regenerative braking, and maintain optimal operating points, thereby achieving high adaptability and efficiency optimization without requiring a complex multi-mode gearbox.
2Adaptability or versatility
If dual motors on a common axis are arranged, then single motor operation is enabled, but the degree of freedom constraint to vehicle speed is not alleviated
Solution Approach 1:
The patent transitions from a one-dimensional common axis arrangement to a two-dimensional configuration where the first motor unit and second motor unit are positioned at different locations (e.g., different wheels or axles). This dimensional change provides an additional degree of freedom, allowing independent speed control of each motor while maintaining operational flexibility for both single and dual motor modes.
3Ease of operation
If a continuously variable transmission is provided, then torque and speed ratio can be controlled independently, but the motor speed is still constrained for a given road speed
Solution Approach 1:
The patent replaces the mechanical CVT system with an electrically-controlled dual motor system. Instead of using mechanical gears and belts to achieve variable transmission ratios, the system uses independent electronic control of two motors to achieve torque and speed optimization. This substitution eliminates the fundamental constraint of motor speed being tied to road speed while maintaining the ability to control torque and speed independently through electronic control algorithms.
Data Source
AI summary
Methods and systems are provided for an electric drive train of a vehicle. In one example, a method may include operating a first motor of a set of motors in a torque control mode at a first speed while operating a second motor of the set of motors in a speed control mode at a second speed. The second speed may be determined based on the first speed and torque may be summed at an output node of a planetary gear set coupled to each of the set of motors.