EV Driver Circuit Short Circuit Detection via PWM Voltage Monitoring
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Solution Overview
Problem
Existing driver circuits for electric vehicles lack an effective method to diagnose when a first voltage driver is shorted to a low voltage and a second voltage driver is shorted to a high voltage, which can lead to operational failures and safety issues.
Innovation Solution
A driver circuit and diagnostic method that utilize a microprocessor to generate pulse width modulated signals and iteratively measure voltages on sense lines to determine filtered voltage values, setting diagnostic flags based on threshold values to identify and address short circuits, thereby controlling the energization of contactor coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage drivers are used to control contactor coils in electric vehicles, then the contactor can be reliably actuated, but short circuits may occur causing safety issues and operational failures
Solution Approach 1:
The system performs preliminary diagnostic actions by continuously monitoring voltage sense lines before faults can cause damage. The microprocessor detects short circuit conditions (first voltage driver shorted to low voltage, second voltage driver shorted to high voltage) through iterative voltage measurements and filtered value comparisons, enabling preventive de-energization of contactor coils before operational failures occur.
Solution Approach 2:
The system implements feedback through voltage sense lines that continuously provide voltage information to the microprocessor. By iteratively measuring voltages on sense lines, calculating filtered voltage values, and comparing against threshold values, the system creates a closed-loop feedback mechanism that detects short circuit conditions and triggers appropriate protective responses.
2Reliability
If diagnostic monitoring is implemented to detect short circuits, then safety is improved, but system complexity increases
Solution Approach 1:
The microprocessor performs multiple functions: it controls the voltage drivers, monitors voltage sense lines for diagnostic purposes, calculates filtered voltage values, and executes protective logic. This multi-functionality consolidates diagnostic capabilities within the existing control unit, avoiding the need for separate dedicated diagnostic hardware and reducing overall system complexity.
Solution Approach 2:
The diagnostic monitoring function is merged with the existing voltage driver control circuitry. The voltage sense lines are integrated into the driver circuit outputs, and the diagnostic logic is combined with the control logic in the microprocessor, creating a unified system that performs both actuation and monitoring without requiring separate independent subsystems.
Data Source
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AI summary
A driver circuit and a diagnostic method are provided. The driver circuit includes a first voltage driver, a second voltage driver, and a microprocessor. The microprocessor generates a first pulse width modulated signal to induce the first voltage driver to output a second pulse width modulated signal to energize a contactor coil. The microprocessor sets a first diagnostic flag equal to a first value if a first filtered voltage value is less than a first threshold value. The microprocessor sets a second diagnostic flag equal to a second value if a second filtered voltage value is greater than a second threshold value. The microprocessor stops generating the first pulse width modulated signal to de-energize the contactor coil if the first and second diagnostic flags are set equal to the first and second values, respectively.