Dual-Motor Gearshift Control for EV Input Shaft Speed Matching
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Solution Overview
Problem
The control of powertrains in electric vehicles, particularly during gear shifting operations, is complex due to the need for coordination between multiple electric machines, leading to inefficiencies and unwanted noise.
Innovation Solution
A controlling apparatus that sets one electric machine in speed control and another in torque control once the input shaft speed is within a target range, allowing for precise speed synchronization and reduced interference, thereby improving control accuracy and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both electric machines are controlled in speed control mode during gear shifting, then speed synchronization is attempted, but interference between machines occurs causing rattling noise
Solution Approach 1:
The patent applies different control modes to different electric machines based on their roles. The first electric machine (primary driver) uses speed control mode to precisely control input shaft speed, while the second electric machine (secondary driver) uses torque control mode to provide torque without actively controlling speed. This local differentiation of control strategies eliminates interference and rattling noise while maintaining speed synchronization.
2Reliability
If multiple electric machines cooperate during gear shifting, then powertrain control is achieved, but control complexity increases
Solution Approach 1:
The patent segments the control functions between two electric machines. The first electric machine is responsible for speed control and reaching target speed, while the second electric machine is responsible for torque control and maintaining torque during the transition. This segmentation simplifies the overall control logic by dividing complex multi-machine coordination into distinct, manageable control tasks.
3Measurement precision
If both electric machines actively control speed, then speed accuracy is improved, but interference and noise increase
Solution Approach 1:
The patent uses the first electric machine as an intermediary that actively controls speed, while the second electric machine acts as a follower that provides torque support without active speed control. The control system mediates between the two machines by allowing the first machine to set the speed reference and the second machine to adapt its torque output, eliminating speed control interference and associated noise.
Data Source
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AI summary
The present invention relates to a controlling apparatus for a powertrain of an electric vehicle, wherein the electric vehicle comprises a gearbox having an input shaft, a first electric machine and a second electric machine being coupled to the input shaft of the gearbox. The controlling apparatus is configured to control the operation of the first and second electric machines by the steps of: - changing the speed of the first and second electric machines to reach a target speed of the input shaft; - determining that the speed of the input shaft is within a target range of the target speed; - setting one of the first and second electric machines in a first control mode, the first control mode being speed control to adjust for changes so that the target speed of the input shaft can be kept when reached, and setting the other one of the first and second electric machines in a second control mode being different to the first control mode, in response of determining that the speed of the input shaft is within the target range.