Low Power Proximity Detection Circuit for EV Charging
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Solution Overview
Problem
Existing proximity detection circuits in battery charging applications consume high quiescent current when the vehicle is in a sleep mode, leading to unnecessary power consumption from the vehicle's batteries.
Innovation Solution
A low power proximity detection apparatus comprising a detection circuit, a hold circuit, and a pulse generator circuit that compares voltage levels at predetermined intervals to determine if a cordset is connected to an external power source, minimizing current draw by only powering the circuit when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the proximity detection circuit operates continuously to detect cordset connection, then the detection reliability is improved, but the quiescent current consumption increases
Solution Approach 1:
The circuit uses a wake-up signal that activates the detection circuit at predetermined intervals instead of continuous operation. The microcontroller enters sleep mode between intervals, and the detection circuit is periodically awakened to check for cordset connection, thereby reducing quiescent current while maintaining detection capability.
Solution Approach 2:
The circuit employs a self-wake-up mechanism where the detection circuit automatically activates upon detecting specific voltage conditions without requiring continuous external control. The hold circuit maintains the wake state until the detection is complete, enabling the system to service itself rather than requiring constant external power management.
2Speed
If the detection circuit is powered continuously, then the response time to detect cordset connection is improved, but the battery power consumption increases
Solution Approach 1:
The circuit performs preliminary detection by monitoring voltage levels on the proximity signal line even when in sleep mode. The hold circuit is pre-configured to immediately activate the detection circuit when specific voltage conditions are met, eliminating wake-up delay while allowing the main processor to remain in low-power state until actual connection detection is needed.
3Measurement precision
If the detection circuit operates at full power, then the measurement precision of voltage comparison is improved, but the power consumption increases
Solution Approach 1:
The circuit applies different power levels to different functional blocks based on their requirements. The detection circuit operates at full power only when actively comparing voltage levels, while the hold circuit and microcontroller operate at reduced power during idle periods. This localized quality adjustment maintains measurement precision when needed while minimizing overall power consumption.
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
The solution effectively reduces quiescent current consumption by intermittently powering the detection circuit and using a flip-flop circuit to store and validate the connection state, ensuring accurate detection while minimizing battery power usage during non-charging periods.
Implementation Method 1
The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to generate a first output indicative of an external power source being electrically coupled to a vehicle
Data Source
AI summary
A proximity detection apparatus including a detection circuit is provided. The detection circuit is configured to receive a proximity signal indicative of a first voltage level and a reference signal indicative of a second voltage level and to receive a wake up signal at predetermined intervals. The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to generate a first output indicative of an external power source being electrically coupled to a vehicle to charge one or more batteries in the vehicle based on the comparison of the first voltage level to the second voltage level.