Electric Drivetrain Torque Converter for Efficient EV Start-Up
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Solution Overview
Problem
Electric motors in purely electric vehicles experience low efficiencies and high thermal loads during start-up processes due to operating in low motor speed ranges, leading to inefficiencies and increased thermal stress on motor poles and inverter elements.
Innovation Solution
The electric drive train incorporates a hydrodynamic torque converter mechanically connected to the motor shaft, which converts motor speed and torque into lower output speed and higher output torque, allowing the electric motor to operate in a more efficient power range, with a liquid cooling system to manage thermal loads and a lock-up clutch to minimize energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor operates during start-up process, then the vehicle can be accelerated from stationary position, but the motor operates in low efficiency range causing high thermal loads
Solution Approach 1:
A hydrodynamic torque converter is introduced as an intermediary device between the electric motor and the transmission system. This torque converter enables the motor to operate in a high-efficiency power range during start-up by converting motor speed and torque into different output characteristics, while still delivering the required start-up torque to the wheels. The torque converter acts as a mediator that decouples the motor's optimal operating range from the vehicle's start-up requirements.
Solution Approach 2:
The system changes the operating parameters of the electric motor during start-up by using the torque converter to transform the motor's speed-torque characteristics. The motor operates at higher speeds and torques (second power range with >80% efficiency) rather than low speeds, and the torque converter transforms these parameters to achieve the required low-speed high-torque output for vehicle acceleration.
2Force
If the electric motor operates in low power range during start-up, then start-up torque can be generated, but thermal loads on motor poles and inverter elements increase
Solution Approach 1:
The hydrodynamic torque converter serves as an intermediary that allows the motor to operate in a favorable power range while still delivering the required start-up torque. By transforming the motor's output characteristics, the torque converter enables the motor to generate torque through high-efficiency operation rather than low-speed operation, thereby reducing thermal loads on motor poles and inverter elements during start-up.
Solution Approach 2:
The patent replaces the conventional direct-drive mechanical connection with a hydrodynamic torque converter system. This substitution allows the motor to operate in a different mechanical regime (higher speed range) while still achieving the required torque output through hydrodynamic transformation, thereby avoiding the thermal stress associated with low-speed high-torque direct operation.
3Loss of energy
If a torque converter is used to convert motor speed and torque, then motor can operate in efficient power range, but device complexity increases
Solution Approach 1:
The hydrodynamic torque converter is designed to perform multiple functions: it transforms motor speed-torque characteristics, enables efficient motor operation during start-up, provides thermal management through integrated cooling, and can operate in different modes (fixed torque ratio, variable torque ratio, fixed speed ratio, variable speed ratio). This multi-functionality justifies the added complexity by delivering comprehensive benefits beyond simple torque transformation.
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 configuration enables the electric motor to operate at higher efficiencies during start-up, reducing thermal loads on motor poles and inverter elements by up to 20% compared to continuous operating conditions, while maintaining an average efficiency greater than 80% and generating a start-up output torque at least 1.5 times the motor torque at low motor speeds.
Implementation Method 1
a start-up support unit mechanically connected to the motor shaft, configured to convert a motor speed and a motor torque of the motor shaft into an output speed and an output torque
Implementation Method 2
the electric motor can include a liquid cooling system which is hydraulically connected to the hydrodynamic torque converter
Data Source
AI summary
An electric drive train for a pure electrically operated vehicle includes an electric motor with a motor shaft and a start-up support unit mechanically connected to the motor shaft configured to convert a motor speed and a motor torque of the motor shaft into an output speed and an output torque such that the output speed is lower than the motor speed and/or the output torque is higher than the motor torque. Also, a method of operating an electric drive train during a start-up process includes increasing a start-up motor speed and a start-up motor torque of a motor shaft of an electric motor, converting the start-up motor speed and the start-up motor torque into a start-up output speed and a start-up output torque with a start-up support unit, and closing a lock-up clutch of the start-up support unit.