Brushless Motor Sensorless Restart Control for Vehicle Doors
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Solution Overview
Problem
DC brushless motor systems in motor vehicle open/close body drive devices face instability and noise issues due to failure of magnetic pole sensors, preventing safe restarting and smooth operation without manual intervention.
Innovation Solution
A control unit in the open/close body drive device detects sensor failures, temporarily stops the motor, and switches to sensorless drive mode by generating a phase switching signal to prolong electric connection patterns, allowing the motor to restart and operate securely without magnetic pole sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic pole sensors are used to detect rotor position for brushless motor control, then motor control precision is improved, but system reliability deteriorates when sensors fail
Solution Approach 1:
The system changes the control parameter from sensor-based position detection to sensorless control based on current feedback. When sensor failure is detected, the control unit switches to a control mode that determines rotor position by monitoring the phase currents and their derivatives, thereby maintaining motor operation without magnetic pole sensors.
Solution Approach 2:
The invention introduces an intermediary control strategy that bridges the gap between sensor failure and motor control. The control unit acts as an intermediary by implementing a dual-mode control system that seamlessly transitions from sensor-based to sensorless control, using current measurements as an intermediary parameter to infer rotor position when sensors are unavailable.
2Object-generated harmful factors
If brush motor rotation speed is reduced to lower noise, then motor noise is reduced, but open/close body movement speed deteriorates
Solution Approach 1:
The system dynamically adjusts motor rotation speed based on real-time operational conditions. The control unit monitors the state of the open/close body and adjusts the motor speed accordingly, allowing high-speed operation when needed (e.g., during initial movement or emergency closing) and low-speed operation when noise reduction is prioritized (e.g., during final positioning or when near the user), thereby resolving the contradiction between noise and speed requirements.
3Shape
If interior handle is removed to improve interior decoration, then aesthetic appearance is improved, but emergency manual operation capability deteriorates
Solution Approach 1:
The motor-driven system provides self-service emergency operation capability through its control unit. When sensor failure or emergency conditions are detected, the control unit automatically activates sensorless control mode and can compulsorily rotate the motor to close the open/close body, eliminating the need for manual intervention via an interior handle while maintaining the aesthetic appearance of the vehicle interior.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the DC brushless motor to securely move the open/close body in any direction, reducing noise and harsh operational sounds, and improves reliability by allowing automatic operation even when magnetic pole sensors fail.
Implementation Method 1
A DC brushless motor, which has stator coils and a rotor magnet, is used as a drive source
Implementation Method 2
a plurality of magnetic pole sensors for detecting positions of magnetic pole positions of a rotor magnet
Data Source
AI summary
The open/close body drive device is capable of restarting a brushless motor, without using magnetic pole sensors, so as to securely drive an open/close body in an arbitrary direction when any of the magnetic pole sensors has failed. When a CPU (1) detects an abnormal logic as a detection pattern of the magnetic pole sensors (9), the CPU (1) determines that the sensor has failed and temporarily stops drive of a DC brushless motor (5), and a motor drive unit (4) generates a phase switching signal to prolong one of electric connection patterns for performing sensorless drive when restarting the DC brushless motor (5).