Hybrid Vehicle VVC Power-Up Sequencing with Self-Test
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Solution Overview
Problem
Existing power-up sequences for hybrid electric vehicles are time-consuming due to predetermined voltage settling periods, leading to potential vehicle shutdowns if voltage converter failures occur during drive cycles, reducing customer satisfaction.
Innovation Solution
A method and system that command voltages across a variable voltage converter, monitor voltage differences, and generate diagnostic signals if thresholds are exceeded, allowing for a self-test and enabling a limited operation mode to ensure safe vehicle operation without a predetermined settling period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined voltage settling period is used in the power-up sequence, then the voltage converter has time to stabilize, but the vehicle startup time increases
Solution Approach 1:
The patent applies preliminary action by performing a self-test of the voltage converter during the power-up sequence before full operation begins. The controller commands a test voltage and monitors the output voltage to detect potential failures early, eliminating the need for a prolonged settling period while ensuring converter stability through active monitoring rather than passive waiting.
Solution Approach 2:
The voltage converter performs self-service through the self-test mechanism where the controller autonomously tests the converter's functionality by commanding a test voltage and monitoring the output. This self-diagnosis capability allows the system to verify converter operation without external intervention or extended settling time, resolving the contradiction between reliability verification and startup speed.
2Reliability
If the voltage converter is tested during the drive cycle, then failures can be detected early, but the testing process adds complexity to the control system
Solution Approach 1:
The patent merges the self-test function with the existing power-up sequence and operational control logic. The controller integrates voltage commanding and monitoring capabilities that are already present for normal operation, using the same hardware and software resources to perform both regular control and diagnostic testing. This consolidation detects failures without adding separate dedicated test equipment or complex external testing systems.
Solution Approach 2:
The controller exhibits multi-functionality by using the same voltage commanding and monitoring circuitry for both normal vehicle operation and diagnostic self-testing. The system universally applies the voltage control mechanism to serve dual purposes: powering the vehicle during operation and testing the converter during power-up and drive cycles. This universal approach enables failure detection without requiring additional specialized testing hardware or control pathways.
Data Source
AI summary
A method for operating a hybrid electric vehicle having a variable voltage converter (VVC) includes commanding a first voltage across a VVC in response to a signal requesting a VVC test, continuously monitoring a first VVC voltage difference over a first calibratable time period, and generating a diagnostic signal if the first voltage difference exceeds a first calibratable threshold for the duration of a first calibratable time period. The method further includes, in response to the first voltage difference dropping below the first calibratable threshold, commanding a second voltage across the VVC, continuously monitoring a second VVC voltage difference over a second calibratable time period, generating a diagnostic signal if the second voltage difference exceeds a second calibratable threshold for the duration of a second calibratable time period, and signaling a test pass in response to the second voltage difference dropping below the second calibratable threshold.