Diagnosing Motor Demagnetization via DC Current Comparison
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Solution Overview
Problem
Eco-friendly vehicles face challenges in diagnosing and managing irreversible demagnetization of permanent magnets in traction motors and hybrid starter-generators, leading to degraded performance and potential driving issues, with existing methods requiring additional hardware and lacking effective torque compensation.
Innovation Solution
A method that diagnoses irreversible demagnetization by comparing DC current values during electricity generation with pre-stored normal values, using existing controller-monitored parameters to determine demagnetization and implement torque compensation control without additional hardware, thereby minimizing performance impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware such as temperature sensors are used to determine demagnetization, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces physical sensors (mechanical/electrical hardware) with a software-based diagnostic method. The controller uses existing electrical parameters (phase currents, voltages, motor operating conditions) to calculate and detect demagnetization through algorithms, eliminating the need for additional temperature sensors or specialized detection hardware while maintaining diagnostic capability
Solution Approach 2:
The system uses its own existing operational data and control parameters to diagnose demagnetization. The controller leverages data already being collected for motor control (currents, voltages, operating mode) to perform self-diagnosis, eliminating the need for external or additional sensing systems
2Reliability
If irreversible demagnetization is not diagnosed and managed, then device complexity remains low, but reliability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors motor operating parameters, compares actual performance against expected values, and detects demagnetization through deviations in electrical characteristics. This closed-loop diagnostic approach enables reliable detection and management of demagnetization without requiring complex external monitoring systems
Solution Approach 2:
The system performs preliminary diagnosis by establishing baseline relationships between motor parameters under normal conditions, then uses these pre-established criteria to detect demagnetization. The controller prepares diagnostic algorithms and comparison criteria in advance, enabling reliable detection when anomalies occur without requiring complex real-time analysis systems
3Measurement precision
If additional hardware is added for demagnetization detection, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent makes the existing controller serve multiple functions: it continues to perform motor control while simultaneously executing demagnetization diagnosis. The same sensors and processing units used for basic motor operation are leveraged for diagnostic purposes, eliminating the need for dedicated detection hardware and simplifying manufacturing
Solution Approach 2:
The diagnostic function is merged with the existing motor control system. The controller integrates demagnetization detection algorithms with routine control operations, combining multiple functions into a single system rather than adding separate diagnostic hardware, thereby reducing manufacturing complexity and cost
Data Source
AI summary
A method for diagnosing demagnetization of a motor of a vehicle can accurately diagnose an irreversible demagnetization state of a permanent magnet of a traction motor or a hybrid starter-generator (HSG) without additional hardware, while minimizing influence of irreversible demagnetization of the permanent magnet of the traction motor or the HSG on vehicle performance. The method includes acquiring operating state information of the motor, determining whether a diagnosis entrance condition including a state in which the motor performs an electricity generating operation is satisfied based on the acquired operating state information of the motor, acquiring a direct current (DC) value in diagnosis, and determining whether irreversible demagnetization occurs by comparing the acquired DC value in diagnosis with a pre-stored DC current value in a normal state of the permanent magnet.