EV High-Voltage Contactor Timing for Arc-Reduced Charging
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Solution Overview
Problem
High voltage contactors in electrified vehicles experience heating and arcing due to variable time delays between closing signals and physical connections, leading to wear and uncertainty in voltage differences across the contactor, which can result in undesirable cumulative effects.
Innovation Solution
A controller predicts the closing time of the contactor based on coil temperature and control signal voltage, generating a low-voltage control signal only when the voltage difference between the high-voltage bus and charger is less than a threshold, reducing the risk of arcing and wear by ensuring the voltage difference is within a desired range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the contactor is closed quickly to reduce connection time, then productivity is improved, but the voltage difference during closing may cause arcing and contactor wear
Solution Approach 1:
The controller predicts the contactor closing time based on coil temperature and control signal voltage before actually closing the contactor. This preliminary prediction allows the system to plan the closing operation in advance, ensuring that voltage thresholds are met at the predicted closing moment, thus enabling faster closing while preventing arcing and wear.
Solution Approach 2:
The system dynamically adjusts the closing decision based on real-time coil temperature and control signal voltage measurements. By continuously monitoring these parameters and updating the predicted closing time, the system optimizes the closing operation to be as fast as possible while maintaining safety margins against arcing and excessive wear.
2Reliability
If the contactor closing time is delayed to ensure voltage stability, then contactor wear is reduced, but the connection time increases
Solution Approach 1:
The controller performs preliminary measurements of coil temperature and control signal voltage to predict the closing time before initiating the closing sequence. This advance planning eliminates unnecessary delays by determining the optimal closing moment in advance, reducing wear while minimizing connection time.
Solution Approach 2:
The system uses feedback from temperature sensors and voltage measurements to continuously refine the predicted closing time. This feedback mechanism ensures that the closing operation is timed optimally, balancing wear reduction with minimal connection time by adjusting the predicted closing time based on actual operating conditions.
3Reliability
If the voltage threshold is lowered to prevent arcing, then contactor reliability is improved, but the system becomes more sensitive to voltage variations
Solution Approach 1:
The system dynamically determines the effective voltage threshold based on the predicted closing time and actual operating conditions. Rather than using a fixed conservative threshold, the threshold is adapted in real-time to account for voltage variations, maintaining reliable arcing prevention while preserving system adaptability to different operating scenarios.
Solution Approach 2:
The controller changes the voltage threshold parameter dynamically based on coil temperature and control signal voltage measurements. By adjusting this critical parameter according to actual conditions, the system maintains optimal protection against arcing while remaining adaptable to varying voltage environments.
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
This approach reduces the time needed to close the contactor while maintaining a desired voltage range, enhancing robustness against operating condition variability and reducing contactor wear, thereby improving system reliability.
Implementation Method 1
a contactor including a coil operable by a low-voltage control signal to selectively electrically couple a terminal of a high-voltage bus to a charger
Data Source
AI summary
An electrified vehicle includes a contactor having a coil operable by a low-voltage control signal to selectively electrically couple a terminal of a high-voltage bus to a charger receiving power from an external source. A programmed controller predicts the time it will take for the contactor to close after receiving a command based on the coil temperature and voltage of the command signal. The controller generates the low-voltage control signal responsive to a difference between bus voltage and charger voltage being less than a first threshold at the predicted closing time of the contactor. The control signal may also depend on the rate of change of the charger voltage being below a second threshold.