Rotating Electric Machine Speed Control for Transmission Input Stability
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Solution Overview
Problem
In vehicle drive systems with an engagement device and a rotating electric machine in the power transfer path between an internal combustion engine and a multi-stage automatic transmission, it is difficult to adjust the input rotational speed of the transmission during shifting operations due to deviations in the transfer torque capacity of the engagement device, leading to degraded drivability.
Innovation Solution
A control device that adjusts the rotational speed of the rotating electric machine according to a predetermined pattern to maintain stable input torque to the multi-stage automatic transmission, correcting any differences in transfer torque capacity to ensure consistent rotational acceleration during shifting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engagement device is brought into a slip engagement state to start the internal combustion engine, then the engine can be started using the torque of the rotating electric machine, but the transfer torque capacity of the engagement device may deviate from target or fluctuate, causing the input rotational speed of the multi-stage automatic transmission to fluctuate and degrading drivability
Solution Approach 1:
The control device calculates the difference between actual and target transfer torque capacity of the engagement device, and uses this feedback to correct the rotational speed command value of the rotating electric machine. This closed-loop feedback control compensates for torque capacity deviations and fluctuations, stabilizing the input rotational speed of the transmission during engine start in electric travel mode.
Solution Approach 2:
The control device dynamically adjusts the rotational speed command value of the rotating electric machine based on the calculated torque capacity difference. By changing the rotational speed parameter in response to actual torque capacity conditions, the system maintains stable transmission input rotational speed despite engagement device torque fluctuations.
2Ease of operation
If feedforward control of torques is performed to adjust the input rotational speed of the multi-stage automatic transmission, then the shifting operation should be optimized, but the control becomes ineffective when the transfer torque capacity of the engagement device deviates from target
Solution Approach 1:
The system supplements feedforward torque control with feedback control by continuously monitoring the actual transfer torque capacity of the engagement device and adjusting the rotating electric machine's rotational speed command accordingly. This combination ensures accurate control even when torque capacity deviates from target values.
Solution Approach 2:
The control device calculates the torque capacity difference in advance and uses it to pre-adjust the rotational speed command value of the rotating electric machine. This preliminary correction compensates for expected torque deviations before they affect the transmission input rotational speed.
Data Source
AI summary
A control device that includes an electronic control unit that causes a rotational speed of the rotating electric machine to change according to a predetermined first change pattern after the rotational speed of the rotating electric machine changes from a pre-shifting synchronous rotational speed in association with progress of the shifting operation until reaching a first synchronous range that is determined on the basis of a rotational speed of the internal combustion engine, the pre-shifting synchronous rotational speed being the rotational speed of the rotating electric machine in a shift speed established before the shifting operation is started.