Power Inverter Test Mode for EV Drivetrain Isolation Fault Detection
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Solution Overview
Problem
Existing fault detection methods in electric vehicle drive trains, such as high-voltage interlock loops, cannot detect motor or cabling faults, posing safety risks and failing to meet functional safety requirements.
Innovation Solution
A power inverter system with two operational modes: an operational mode for normal operation and a test mode for fault detection, utilizing a test unit to determine potential differences between electrically isolated paths to identify isolation faults and winding issues in the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional high-voltage interlock loop methods are used for fault detection, then the system structure remains simple, but the detection capability is insufficient and cannot detect motor or cabling faults
Solution Approach 1:
The patent performs fault detection before connecting the high-voltage battery by applying low voltage through the inverter to test motor windings and cabling. This preliminary action identifies potential faults before high-voltage operation, preventing dangerous situations while maintaining system safety through proactive testing rather than reactive detection.
Solution Approach 2:
The patent introduces a low-voltage test mode as an intermediary between system initialization and high-voltage operation. This intermediary testing phase uses isolated low-voltage signals to probe the motor and cabling for faults, serving as a safe mediator that verifies system integrity without exposing the system to high-voltage risks.
2Reliability
If fault detection is performed after connecting high voltage, then the operational mode is maintained, but safety risks increase due to undetected faults
Solution Approach 1:
The system performs safety-critical fault detection during the pre-charge phase before high-voltage battery connection. By detecting motor winding faults, open circuits, and cabling issues beforehand, the system ensures safety is verified in advance, eliminating the need for delayed detection and preventing dangerous high-voltage operation with undetected faults.
Solution Approach 2:
The patent applies preliminary anti-action by preventing high-voltage connection when faults are detected during low-voltage testing. The system proactively identifies potential failure modes and blocks the transition to high-voltage operation, counteracting safety risks before they can manifest during actual motor operation.
3Productivity
If the high voltage battery is connected immediately without testing, then the operational readiness is achieved quickly, but potential faults remain undetected creating safety hazards
Solution Approach 1:
The system implements a rapid low-voltage test sequence that quickly assesses motor and cabling integrity before high-voltage connection. This preliminary testing action occurs during the pre-charge phase, adding minimal time to system initialization while effectively identifying faults that would create safety hazards during high-voltage operation.
Solution Approach 2:
The patent enables the system to quickly skip the testing phase when no faults are detected, allowing rapid transition to high-voltage operation. The low-voltage test mode can be executed and completed in minimal time, and if passable, the system rushes through to operational mode without delay, maintaining productivity while eliminating safety hazards.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables early detection of isolation faults and winding issues before connecting high voltage, reducing safety risks and ensuring compliance with functional safety standards.
Implementation Method 1
a test unit configured to determine an indication of a potential difference between the first and second electrical paths; the test unit may comprise a current sensor. The test unit may be configured to determine an indication of a potential difference between the first and second electrical paths by measuring current flow in one or both of the first and second electrical paths.
Data Source
AI summary
A power inverter for an electric drive chain of a vehicle, comprising: a first electrical path connectable to a high voltage source and a low voltage source; a second electrical path that is connectable to the first electrical path and also capable of being electrically isolated from the first electrical path; and a test unit configured to determine an indication of a potential difference between the first and second electrical paths; the power inverter being configured to have two modes of operation: an operational mode in which the first electrical path is connected to the high voltage source and the power inverter is configured to provide current to an electric motor of the vehicle; and a test mode in which the first electrical path is connected to the low voltage source and the test unit is configured to determine, from the indication of the potential difference between the first and second electrical paths, whether there is a fault in an electrical connection in the vehicle.