Electric Vehicle Motor Efficiency via Planetary Gear Brake Control
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Solution Overview
Problem
The existing electric vehicle drive systems with a planetary gear mechanism suffer from reduced motor efficiency due to the simultaneous operation of vehicle and air-conditioner drive motors, leading to shorter travel distances for the same battery capacity and increased battery size for the same travel distance.
Innovation Solution
An electric vehicle configuration with a second drive motor coupled to the drive wheels and a first drive motor for the air-conditioner compressor, utilizing a planetary gear device with a brake to selectively engage or disengage the compressor, allowing high-acceleration travel with both motors and normal travel with a single motor, optimizing motor efficiency through electronic control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If both the vehicle drive motor and air-conditioner drive motor are operated simultaneously to provide high drive force, then high-acceleration performance is achieved, but motor efficiency decreases due to low load on each motor
Solution Approach 1:
The system dynamically switches between single-motor and dual-motor operation modes based on drive force requirements. The brake device selectively engages or disengages the air-conditioner drive motor from the planetary gear mechanism, allowing the vehicle drive motor to operate alone during normal travel (maintaining high efficiency) and enabling both motors to operate together during high-acceleration scenarios (providing sufficient power).
Solution Approach 2:
The air-conditioner drive motor is extracted from the continuous dual-motor configuration and selectively coupled to the planetary gear mechanism through the brake device. This allows the system to separate the air-conditioning function from the vehicle propulsion function, enabling the vehicle drive motor to operate independently at optimal load during normal travel, thereby maintaining high motor efficiency.
2Adaptability or versatility
If the air-conditioner compressor is continuously coupled to the planetary gear mechanism, then the compressor can be driven by the first drive motor, but the vehicle drive motor cannot operate at high efficiency due to load distribution
Solution Approach 1:
The brake device provides dynamic engagement and disengagement of the air-conditioner drive motor with the planetary gear mechanism. During normal vehicle travel, the brake disengages the air-conditioner drive motor, allowing the vehicle drive motor to operate alone at high efficiency. When air-conditioning is needed, the brake engages the air-conditioner drive motor to the planetary gear mechanism, enabling the compressor to be driven while the vehicle drive motor can still provide propulsion.
3Loss of energy
If a single motor is used for vehicle propulsion, then motor efficiency is high during normal travel, but high-acceleration performance is insufficient
Solution Approach 1:
The planetary gear mechanism serves multiple functions: it transmits power from the vehicle drive motor to the drive wheels during normal travel, and it combines the output of both the vehicle drive motor and air-conditioner drive motor during high-acceleration scenarios. The brake device enables this multi-functionality by selectively coupling or decoupling the air-conditioner drive motor from the planetary gear mechanism based on driving conditions.
Solution Approach 2:
During high-acceleration scenarios, the system merges the output of the vehicle drive motor and the air-conditioner drive motor through the planetary gear mechanism. The brake device engages both motors to the planetary gear mechanism, allowing their combined torque to be transmitted to the drive wheels, thereby achieving high-acceleration performance that would be insufficient with a single motor.
Data Source
AI summary
An electric vehicle includes: a second drive motor that is coupled to drive wheels to rotationally drive the drive wheels; a compressor that activates an air conditioner; a first drive motor that can drive the compressor; a planetary gear device that includes a first rotary element to which the second drive motor is coupled, a second rotary element to which the compressor is coupled, and a third rotary element to which the first drive motor is coupled; and a brake that selectively couples the compressor to a non-rotary member when the brake is engaged.