Adaptive Pre-Charge Circuit for PWM Overcurrent Detection
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Solution Overview
Problem
Existing pre-charge circuits in electric vehicles struggle to reliably detect overcurrent faults during fast PWM-based precharge functions, especially in systems with varying battery voltages, leading to potential component damage from high inrush currents.
Innovation Solution
An adaptive pre-charge control circuit using pulse width modulation (PWM) to generate a defined current profile, monitoring current and voltage increments, and implementing overcurrent fault detection through specific current patterns and voltage measurements to ensure safe charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PWM control is used for fast pre-charge function, then pre-charge speed is improved, but overcurrent fault detection reliability deteriorates
Solution Approach 1:
The patent applies periodic action by using PWM (pulse-width modulation) control to generate periodic current pulses during pre-charge. The controller issues PWM signals that create a defined current profile with alternating pulses, enabling both fast charging and reliable fault detection through pattern recognition of consecutive pulse exceedances.
Solution Approach 2:
The patent implements feedback by continuously monitoring the current profile during pre-charge and comparing it against the defined PWM pattern. The controller detects overcurrent faults by identifying when two consecutive pulses exceed the predefined limit, using this feedback information to distinguish normal operation from actual fault conditions and trigger appropriate protection responses.
2Object-affected harmful factors
If pre-charge control limits inrush current, then component protection is improved, but charging speed deteriorates
Solution Approach 1:
The patent resolves this contradiction by using periodic PWM pulses instead of continuous current limiting. The alternating pulse pattern allows controlled inrush current during off-pulses for protection while enabling faster charging during on-pulses, achieving both component protection and acceptable charging speed through time-based current management.
Solution Approach 2:
The patent applies dynamics by making the pre-charge current profile dynamic through PWM modulation rather than static resistance-based limiting. The controller dynamically adjusts current delivery in pulses, adapting the charging rate while maintaining protection thresholds, thus achieving both speed and protection objectives through dynamic control.
Data Source
AI summary
Disclosed is an adaptive pre-charge control circuit, for use in a solid state battery disconnect and protection system, wherein the adaptive pre-charge control circuit includes a high-voltage switch coupled between an electric battery and a DC link capacitor of an electric vehicle, and wherein the electric vehicle is powered by the electric battery. The control circuit may be operable to issue a pulse width modulated (PWM) signal to generate a current profile wherein every other pulse exceeds a predefined limit, monitor, during pre-charging, the current profile, and to determine an overcurrent fault exists in the case that two consecutive pulses exceed the predefined limit.