Motor Control Unit Failure Detection via Current Difference Comparison
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Solution Overview
Problem
Existing motor control units for three-phase motors with multi-system windings struggle to reliably detect failures such as short-circuit or disconnection issues in driving circuits, often due to small current variations or noise interference, which can lead to undetected failures and reduced operational reliability.
Innovation Solution
A motor control unit that detects phase currents for each winding system, converts them to a two-phase or three-phase coordinate system, and uses a failure diagnosing section to compare current differences with accumulated values against predetermined thresholds, ensuring accurate failure detection and continuous operation by isolating faulty systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current detection methods are used for multi-system motor windings, then the device complexity is reduced, but the reliability of failure detection deteriorates due to small current variations or noise interference
Solution Approach 1:
The patent divides the motor control into multiple independent winding systems (first system and second system), each with separate current detection and control circuits. This segmentation allows independent monitoring of each system, enabling reliable failure detection by comparing current variations between systems without requiring complex centralized detection mechanisms.
Solution Approach 2:
The patent implements feedback control by detecting currents in each winding system, calculating current variations, and using these variations to diagnose failures. The feedback mechanism continuously monitors current differences between the first and second winding systems, enabling real-time failure detection while maintaining relatively simple control architecture.
2Productivity
If multi-system motor windings are used, then the productivity and continuous operation capability are improved, but the difficulty of detecting and measuring failures increases due to overlapping current paths
Solution Approach 1:
The patent segments the motor windings into distinct first and second systems with separate current detection circuits. This segmentation creates independent measurement paths for each system, allowing failures to be detected by comparing current variations between systems without interference from overlapping current paths, thus reducing detection difficulty while maintaining continuous operation capability.
Solution Approach 2:
The patent applies local quality by providing dedicated current detection and control circuits for each winding system. Each system has its own detection circuit tailored to its specific current characteristics, enabling precise local monitoring that simplifies failure detection despite the complexity of multi-system operations.
3Measurement precision
If conventional failure detection methods are used, then the device complexity is minimized, but the measurement precision of current variations deteriorates due to noise interference
Solution Approach 1:
The patent uses feedback control to continuously monitor current variations in each winding system and compare them against expected values. By implementing feedback mechanisms that track current changes over time and across systems, the patent achieves high measurement precision for detecting small current variations caused by failures, while keeping the control unit complexity manageable through systematic monitoring approaches.
Solution Approach 2:
The patent segments the current detection into separate circuits for each winding system, allowing independent precision measurement of current variations in each system. This segmentation enables the use of optimized detection methods for each system without being constrained by the need to process all currents through a single complex detection mechanism, thereby improving measurement precision while controlling complexity.
Data Source
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AI summary
[Problem] The present invention provides a high reliable motor control unit that surely detects and processes a failure of driving circuits for a motor with multi-system motor windings, such as an opening failure or a short-circuit failure of switching elements, a disconnection failure or a short-circuit failure of coil windings, or a disconnection failure or a short-circuit failure of other driving circuits, a failure detecting method, an electric power steering apparatus and a vehicle equipped with the motor control unit. [Means for solving the problem] Amotor control unit that controls amotorwithmulti-system windings via motor driving circuits on winding systems based on a current command value comprising: current detecting circuits to detect at least two-phase or more currents for each of the multi-system windings of the three-phase motor, three-phase/two-phase converting sections to convert the detected phase currents to two-phase currents for the multi-system windings, and a failure diagnosing section to perform a current-calculation of the two-phase currents converted to two-phase for the multi-system windings, and to perform a diagnosis failure by comparing a difference of current-calculated results between the multi-system windings and an accumulating value of the difference with respective thresholds.