Vehicle Motor Control Apparatus Intermittent Lock Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle control systems face challenges in determining intermittent motor lock states, which can cause switching element temperature rises, and increasing the motor rotation speed threshold to address this issue leads to drivability degradation.
Innovation Solution
A vehicle control apparatus that performs first and second torque restriction controls based on specific motor torque and rotation speed conditions, with the second determination time being longer than the first, to protect the switching element from temperature rise while maintaining drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the threshold of the motor rotation speed is increased to detect intermittent motor lock, then the motor lock state can be determined, but the region determined as motor lock becomes wider, making motor torque more likely to be restricted, which degrades drivability during normal driving
Solution Approach 1:
The motor lock detection is divided into two separate determination processes: first determination for continuous lock detection (using first torque threshold and first rotation speed threshold) and second determination for intermittent lock detection (using second torque threshold and second rotation speed threshold). This segmentation allows each determination to use optimized thresholds for its specific purpose, preventing the need to raise the first threshold which would degrade drivability.
Solution Approach 2:
The system dynamically switches between different determination modes based on the current operating conditions. The control unit performs first determination when continuous motor lock is suspected, and second determination when intermittent motor lock is suspected. This dynamic approach allows the system to adapt the detection sensitivity to the actual motor lock pattern, maintaining high detection accuracy without unnecessarily restricting torque during normal driving.
2Reliability
If the motor torque is restricted to protect the switching element from temperature rise, then the switching element is protected, but the motor torque is reduced, which may affect vehicle performance
Solution Approach 1:
The control unit performs preliminary determination of motor lock state before the switching element temperature can rise significantly. By detecting motor lock conditions (both continuous and intermittent) in advance and restricting motor torque proactively, the system prevents temperature rise in the switching element while minimizing the impact on motor torque by only restricting torque when motor lock is actually detected.
Solution Approach 2:
The system changes the torque threshold parameters based on the determined motor lock pattern. When continuous motor lock is detected, the first torque threshold is applied; when intermittent motor lock is detected, the second torque threshold is applied. This parameter adaptation allows appropriate torque restriction levels that protect the switching element while maintaining optimal vehicle performance for each lock pattern.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To provide a vehicle control apparatus capable of protecting a switching element from temperature rise caused by intermittent motor lock while preventing drivability degradation. [Solution] Included are a motor (4), an inverter (5) that supplies AC electric power to the motor (4) using a switching element and a control unit (6) that performs first torque restriction control to restrict torque of the motor (4) in a case where a first determination condition that the torque of the motor (4) is equal to or larger than first torque and that a rotation speed of the motor (4) is equal to or less than a first rotation speed is met for a first determination time, performs second torque restriction control to restrict the torque of the motor (4) in a case where a second determination condition that the torque of the motor (4) is equal to or larger than second torque which is smaller than the first torque and that the rotation speed of the motor (4) is equal to or less than a second rotation speed which is higher than the first rotation speed is met for a second determination time, and makes the second determination time longer than the first determination time.