EV Torque Estimation During Fault Conditions
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Solution Overview
Problem
Electric vehicles lack effective methods to accurately estimate motor torque during fault conditions, such as three-phase short or open circuits, which can lead to hazardous situations without dedicated torque sensors, and existing diagnostic routines fail to provide accurate torque estimation during these events.
Innovation Solution
The system employs a processing unit to run diagnostic routines, determine motor speed, and differentiate between three-phase short and open circuit fault conditions, estimating motor torque based on speed and fault type to control the drive system and maintain vehicle operation safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no torque sensor is used to reduce system complexity and cost, then device complexity is reduced, but torque measurement precision deteriorates during fault conditions
Solution Approach 1:
The patent uses current sensors as intermediary devices to indirectly measure torque during fault conditions. Instead of directly measuring torque with a torque sensor, the system measures phase currents and uses these measurements as intermediaries to calculate estimated torque values through diagnostic routines and mathematical models.
Solution Approach 2:
The patent replaces the mechanical torque sensing system with an electrical measurement system. By substituting physical torque sensors with electrical current measurements and computational algorithms, the system achieves torque estimation during fault conditions without the complexity and cost of dedicated torque sensing hardware.
2Ease of operation
If diagnostic routines are simplified to reduce processing requirements, then ease of operation is improved, but fault detection accuracy deteriorates
Solution Approach 1:
The patent segments the diagnostic process into distinct routines for different fault types (three-phase short circuit, three-phase open circuit, single-phase faults). Each diagnostic routine is specialized for detecting specific fault conditions, allowing the system to maintain high detection accuracy while keeping individual routines computationally efficient and easy to implement.
Solution Approach 2:
The patent implements preliminary diagnostic checks that continuously monitor phase currents and voltage signals before fault conditions fully develop. By performing preliminary detection of abnormal current patterns, the system can identify incipient faults early and trigger appropriate diagnostic routines, improving overall detection accuracy without requiring complex real-time analysis during critical fault events.
Data Source
AI summary
The present disclosure generally relates to operating an electric vehicle (EV) during a fault condition. The EV drive system comprises a motor configured to provide motive force to the EV. The EV processing system can to run a diagnostic routine to monitor the drive system for the fault condition. In response to identifying that the drive system is in the fault condition, the processing system can determine whether the fault condition was caused a three-phase short circuit or a three-phase open circuit. The processing system can estimate a motor torque for the motor based at least partly on the motor speed and on whether the fault condition was caused by the three-phase short circuit or the three-phase open circuit, and can use the estimated motor torque to control the drive system to provide motive force to the EV while operating in the fault condition.