Shift-by-Wire Motor Control Apparatus Current Learning
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Solution Overview
Problem
Existing shift-by-wire systems face reduced accuracy in standard position learning control due to changes in motor winding resistance caused by temperature and chronological changes, and are prone to malfunctions if current detecting or current limiting circuits fail.
Innovation Solution
A control apparatus with switching devices, a current detecting circuit, a current limit circuit, and an error determination device that restricts current changes through windings and detects malfunctions, ensuring accurate standard position learning and preventing control loss by determining if the current detecting or current limit circuits malfunction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current limit circuit is added to restrict current changes, then accuracy of standard position learning is improved, but device complexity increases
Solution Approach 1:
The control apparatus merges the current detecting circuit and current limit circuit into a unified current control system that works together to maintain accurate standard position learning. The current detecting circuit monitors phase currents and feeds this information to the current limit circuit, which adjusts the current commands to maintain the average current within a predetermined range, thereby resolving the technical contradiction by integrating multiple functions into a coordinated system.
Solution Approach 2:
The system implements feedback control where the current detecting circuit continuously monitors the actual phase currents and feeds this information back to the controller. The controller uses this feedback to adjust the current commands through the current limit circuit, ensuring that the average current remains within the predetermined range despite temperature changes or chronological degradation, thus maintaining learning accuracy without requiring overly complex external control systems.
2Measurement precision
If physical circuits for current detection and limitation are added, then current control accuracy is improved, but reliability decreases due to potential circuit damage
Solution Approach 1:
The control apparatus implements beforehand cushioning by incorporating redundant error determination devices that monitor the operational status of the current detecting circuit and current limit circuit. These error determination mechanisms detect malfunctions before they lead to complete system failure, allowing for preventive measures or graceful degradation. This approach maintains current control accuracy while compensating for the reduced reliability inherent in adding physical circuits.
Solution Approach 2:
The system employs self-service through automatic error detection and diagnosis capabilities. The error determination device continuously monitors the health of the current detecting and limiting circuits, and when malfunctions are detected, the system can automatically switch to alternative operational modes or alert the operator, reducing the need for external intervention and maintaining system reliability despite the presence of additional physical circuits that could fail.
3Reliability
If error determination device is added to detect circuit malfunctions, then system reliability is improved, but device complexity increases
Solution Approach 1:
The error determination device is designed with multi-functionality, serving both as a monitoring mechanism for circuit health and as part of the overall control logic. It integrates with the existing controller and can perform multiple functions including error detection, error classification, and triggering appropriate response actions. This universal approach improves system reliability without proportionally increasing device complexity, as the same hardware resources are utilized for multiple purposes.
Data Source
AI summary
A control apparatus controlling a motor for driving an object to switch a shift range of a transmission includes: switching devices for energization to windings of the motor; a controller for the switching devices; a current detecting circuit for a current in the windings and the switching device; a current limit circuit keeping an average of the current within a predetermined range; a standard position learning device of the motor at a learning range such that the current limit circuit limits the current, and the motor rotates until the object stops at a limit position of a movable range; a shift range determination device; and an error determination device determining that the current detecting circuit or the current limit circuit malfunctions when the object does not reach the limit position, the shift range is in a non-learning range, and the standard position learning device starts to learn the standard position.