Dual Planetary EV Drive Shifting Without Power Interruption
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Solution Overview
Problem
Existing electric vehicles with two planetary gear sets experience power interruption and jerking during gear shifting due to torque removal and reapplication, leading to a poor riding experience.
Innovation Solution
An electric drive system with two planetary gear sets that utilizes a control mechanism to maintain uninterrupted power during gear shifting by connecting the first planet carrier to the transmission housing or ring gear, allowing the first motor to drive the system output shaft independently and adjusting the second motor's torque to minimize power interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque removal is implemented during gear shifting, then the gear can be shifted into neutral, but power interruption occurs
Solution Approach 1:
The transmission system is divided into two independent planetary gear sets (first and second planetary gear sets), each capable of providing torque to the output shaft. This segmentation allows one gear set to maintain power delivery while the other undergoes gear shifting operations, thereby preventing power interruption.
Solution Approach 2:
The first planetary gear set acts as an intermediary power source during gear shifting of the second planetary gear set. When the second planetary gear set is shifting into neutral, the first planetary gear set continues to drive the output shaft, serving as a mediator that maintains power continuity throughout the transition.
2Ease of operation
If torque reapplication is implemented after gear shifting, then the gear is engaged, but jerking and poor riding experience occur
Solution Approach 1:
The first planetary gear set is prepared in advance to take over power delivery before the second planetary gear set completes its shifting. This preliminary arrangement ensures that torque is already being applied to the output shaft through the first planetary gear set, preventing the jerking that would occur from sudden torque reapplication.
Solution Approach 2:
The system ensures continuous torque delivery to the output shaft by having the first planetary gear set maintain power transmission during the entire gear shifting process. This continuity of useful action eliminates interruptions and jerking, providing smooth power delivery throughout the gear engagement process.
3Device complexity
If a fixed-speed-ratio drive system is used, then the structure is simplified, but maximum speed and high-torque output cannot be balanced
Solution Approach 1:
The system employs two planetary gear sets with different fixed speed ratios, allowing the transmission to dynamically switch between different gear configurations. By engaging or disengaging the first planetary gear set, the system can adapt between high-torque low-speed mode (second planetary gear set engaged) and high-speed mode (first planetary gear set engaged), achieving versatility without complex variable-ratio mechanisms.
Data Source
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AI summary
The present invention pertains to the technical field of electric drive systems, and specifically relates to an electric drive system having two planetary gear sets, a vehicle and a gear shifting method. The electric drive system includes a transmission housing, a first motor, a second motor, a first planetary gear set, a second planetary gear set, a connecting device, and a system output shaft. The first planetary gear set includes a first sun gear, a first ring gear, and a first planet carrier. The second planetary gear set includes a second sun gear, a second ring gear, and a second planet carrier. A rotor of the first motor is connected to the second sun gear, and a rotor of the second motor is connected to the first sun gear. The first planet carrier is connected to the second ring gear; and the second planet carrier is connected to the first ring gear and the system output shaft respectively. The connecting device is configured to fixedly connect the first planet carrier to the transmission housing, or fixedly connect the first planet carrier to the first ring gear. By the electric drive system having two planetary gear sets according to the present invention, power of the vehicle is not interrupted in a gear shifting process, thereby improving performance of an electric vehicle.