Motor Rotational Angle Detection Using Redundant Sensor Reference
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Solution Overview
Problem
Conventional motor rotational angle detection systems with duplexed sensors fail to accurately identify abnormalities, such as broken wires or short circuits, leading to inability to continuously output normal rotational angles when faults occur in any of the sensors.
Innovation Solution
A motor rotational angle detection device with multiple units, including a main sensor, sub-sensor, and redundant sensor, where a normal angle decision device compares output values to identify and output a normal rotational angle even when an abnormality occurs, ensuring continuous operation by using the redundant sensor as a reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplexed sensors are provided to detect sensor faults, then sensor fault detection capability is improved, but abnormality identification accuracy deteriorates when broken wires or short circuits occur
Solution Approach 1:
The patent introduces a third sensor as an intermediary reference point to mediate between the two primary sensors. When comparing sensor outputs, the third sensor serves as a neutral reference to determine which of the first two sensors is faulty, enabling accurate identification of broken wires or short circuits that would otherwise be indistinguishable using only two sensors.
Solution Approach 2:
The patent changes the parameter of sensor quantity from two to three, fundamentally altering the comparison logic. This parameter change enables the system to distinguish between different fault modes (broken wire vs. short circuit) by comparing all three sensor outputs against each other, rather than simply checking for agreement between two sensors.
2Reliability
If multiple sensors are included for redundancy, then system reliability is improved, but the ability to identify which sensor is faulty deteriorates
Solution Approach 1:
The third sensor acts as an intermediary reference that simplifies fault identification. By comparing all three sensors against each other, the system can clearly identify which sensor is faulty based on which sensor's output deviates from the other two, making fault detection straightforward rather than complex.
Solution Approach 2:
The patent uses three copies of the same sensor type to detect rotational angle. This redundant copying approach ensures that if one copy is faulty, the other two healthy copies can provide accurate measurements and serve as a reference to identify the faulty one, maintaining system reliability while enabling fault identification.
3Device complexity
If conventional duplexed sensor comparison is used, then simple fault detection is achieved, but continuous normal output cannot be ensured when faults occur
Solution Approach 1:
The patent applies local quality by assigning different roles to different sensors based on their operational state. When a fault is detected in one sensor, the system locally adapts by using the other two sensors as the active measurement source, ensuring continuous normal output while maintaining simple detection logic.
Solution Approach 2:
The system prepares in advance for potential sensor failures by having three sensors instead of two. This beforehand cushioning ensures that when a fault occurs, there are still at least two healthy sensors available to provide accurate measurements, preventing system failure and ensuring continuous normal output capability.
Data Source
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AI summary
According to a motor rotational angle detection device which includes a plurality of motor rotational angle detection units (6 and 7) which detect a rotational angle of a motor (1), and a normal angle decision device (8) which includes a motor rotational angle information item and decides a normal motor rotational angle, in which when a difference is caused between output values of the plurality of motor rotational angle detection units (6 and 7), the normal angle decision device (8) respectively compares the output value of each of the motor rotational angle detection units (6 and 7) with the motor rotational angle information item included in the normal angle decision device (8), and identifies the normal motor rotational angle detection unit, and decides the normal motor rotational angle.