EV Battery Charger Enable Circuit for Stable Control Pilot Transitions
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Solution Overview
Problem
Existing vehicle battery charging systems face instability in enabling the power supply chip due to varying control pilot signal sequences, leading to inconsistent charging, especially when the signal directly transitions from a non-power state to a power state, resulting in repeated enabled and disabled states and potential failure to charge the vehicle battery.
Innovation Solution
A vehicle battery charging apparatus with a power supply chip enabled by a chip enable circuit that adjusts the voltage level of the chip enable signal based on the control pilot signal, using an RC circuit and operational amplifier to maintain the voltage level above a preset threshold, ensuring stable power supply regardless of the control pilot signal's frequency and duty ratio, and utilizing internal power instead of auxiliary battery power to reduce costs and area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the power supply chip is enabled based on direct control pilot signal input, then the charging apparatus can respond quickly to charging commands, but the power supply becomes unstable when the signal transitions directly from non-power state to power state
Solution Approach 1:
The RC circuit performs preliminary voltage smoothing and filtering on the control pilot signal before it reaches the power supply chip enable input. By charging the capacitor through the resistor, the circuit prepares a stable voltage level in advance, preventing direct transitions that cause instability while maintaining quick response to legitimate charging commands.
Solution Approach 2:
The RC circuit acts as a cushioning element between the control pilot signal and the power supply chip enable input. The capacitor stores energy and provides voltage cushioning during signal transitions, absorbing sudden voltage changes and preventing direct state transitions that would cause the power supply to flicker between enabled and disabled states.
2Reliability
If auxiliary battery power is used to maintain the power supply chip enabled state, then the chip remains stable, but the auxiliary battery discharges excessively and the system cost and area increase
Solution Approach 1:
The power supply chip maintains its enabled state using its own internal power consumption characteristics and the smoothed control pilot signal voltage, rather than continuously drawing power from the auxiliary battery. The RC circuit enables the chip to self-maintain its state through proper voltage level holding, eliminating the need for continuous auxiliary battery power supply.
Solution Approach 2:
The invention extracts the power supply stability function from the auxiliary battery and transfers it to the RC circuit voltage smoothing mechanism. By removing the dependency on auxiliary battery power for maintaining the enabled state, the system reduces auxiliary battery discharge while maintaining chip stability through the passive RC voltage holding capability.
3Adaptability or versatility
If the control pilot signal frequency and duty ratio are varied according to different EVSE types, then the system adapts to different charging standards, but the power supply chip enable state becomes inconsistent
Solution Approach 1:
The RC circuit provides a universal voltage smoothing function that works consistently across different control pilot signal frequencies and duty ratios. The resistor-capacitor time constant is designed to be effective across the range of signal variations from different EVSE types, making the power supply enablement behavior consistent regardless of which charging standard or EVSE type is being used.
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 stabilizes the power supply to the vehicle battery charging apparatus, ensuring consistent charging, reducing costs and area consumption, and alleviating auxiliary battery discharge, while allowing for safe and effective charging regardless of the EVSE's control pilot communication sequence.
Implementation Method 1
an RC circuit including a resistor having a resistance and a capacitor having a capacitance, and the RC circuit may adjust the voltage level of the chip enable signal to a preset voltage level or higher by charging/discharging the capacitor according to a time constant determined by the resistance and the capacitance
Implementation Method 2
an operational amplifier configured to receive the control pilot signal through a non-inverting input terminal based on the internal power supply voltage, buffer the control pilot signal, and output the control pilot signal to the RC circuit
Data Source
AI summary
An embodiment vehicle battery charging apparatus includes a power supply chip enabled according to voltage levels of a control pilot signal and a chip enable signal to supply an internal power supply voltage, a charging controller configured to receive the internal power supply voltage and control charging of a vehicle battery based on the control pilot signal, and a chip enable circuit configured to receive the internal power supply voltage, receive the control pilot signal, and adjust a voltage level of the chip enable signal based on a voltage level of the control pilot signal to enable the power supply chip.