Precharge Controller Sensor Failure Detection
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Solution Overview
Problem
Existing precharge controllers fail to accurately determine precharge completion when a current sensor is faulty, leading to potential damage from inrush currents when the main contactor is closed prematurely.
Innovation Solution
A precharge controller that uses an electronic control unit (ECU) to detect current sensor failures before starting precharging, prohibiting precharge if the sensor is faulty and determining completion based on threshold current values to prevent false determinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precharge completion is determined based on current value after predetermined time, then precharge control can be implemented, but false determination occurs when current sensor fails
Solution Approach 1:
The system performs preliminary detection of current sensor status before starting precharge by checking whether current value is within expected range during initial phase. This preliminary check prevents false precharge completion determination by identifying sensor failures before they can cause incorrect control decisions.
Solution Approach 2:
The system continuously monitors current sensor output during precharge operation and compares it against expected characteristics. When sensor readings deviate from expected patterns (indicating failure), the system provides feedback to prohibit precharge or adjust control strategy, ensuring reliable operation despite sensor issues.
2Productivity
If main contactor is closed without verifying precharge completion, then system operation is faster, but inrush current damages main contactor
Solution Approach 1:
The system performs preliminary precharge operation before closing the main contactor, ensuring capacitor is charged to appropriate voltage level. This preliminary charging action prevents dangerous inrush current when main contactor closes, protecting the contactor while enabling safe rapid operation.
Solution Approach 2:
The precharge contactor and resistor are activated beforehand to create a controlled charging path that opposes the harmful inrush current effect. This preliminary anti-action neutralizes the potential damage before the main contactor closes, allowing both fast operation and component protection.
3Ease of operation
If current sensor is not checked before precharge, then system startup is simpler, but sensor failure causes incorrect precharge control
Solution Approach 1:
The system performs preliminary sensor functionality verification as part of the startup sequence by checking current readings against expected values before initiating precharge. This preliminary check integrates seamlessly into startup procedure while ensuring sensor reliability for accurate precharge control.
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
Prevents premature closure of the main contactor, avoiding potential failures by ensuring accurate precharge completion determination and notifying the driver of sensor failures, thus preventing damage and ensuring safe operation.
Implementation Method 1
a precharge contactor connected in parallel with the main contactor, and forming another power supply path via a current limiting resistor
Data Source
AI summary
A precharge controller includes a main contactor, a capacitor, a precharge contactor, a current sensor, and a control unit. When starting a power supply from a battery to load, the control unit starts precharging by closing the precharge contactor when a detected current is equal to a preset value or lower, determines completion of precharging when the detected current once equal to or exceeded a first threshold value falls to a second threshold value or lower, and closes the main contactor.