Ultra-capacitor Series Bypass Circuit for Vehicle Power Transients
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Solution Overview
Problem
Modern vehicles impose large continuous and transient currents on SLA batteries due to increased load demands, making it difficult for them to support these currents effectively due to internal resistance characteristics.
Innovation Solution
A vehicle power system is designed with an ultra-capacitor and a bypass circuit, where the ultra-capacitor is electrically coupled in series with the SLA battery, allowing the ultra-capacitor to handle transient current events and maintain a higher floating voltage, while the bypass circuit prevents over-discharging and polarity reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If SLA batteries are used to support large continuous and transient currents in modern vehicles, then the power delivery capability is improved, but the internal resistance causes voltage drops and reduces reliability during transient events
Solution Approach 1:
The power system is segmented into two distinct energy storage components: SLA batteries for continuous power delivery and ultra-capacitors for transient current events. This segmentation allows each component to operate in its optimal performance range, with the ultra-capacitor handling high-rate transients and the battery providing sustained power, thereby resolving the contradiction between power delivery and voltage stability.
Solution Approach 2:
The patent merges SLA batteries and ultra-capacitors into a hybrid power system where both components work together through a control circuit. The ultra-capacitor module is electrically connected in parallel with the battery, creating a unified power source that combines the high power density of capacitors with the high energy density of batteries, achieving both improved power delivery and voltage stability.
2Reliability
If ultra-capacitor is added to handle transient current events, then voltage stability during transients is improved, but the system complexity increases due to additional components and control circuitry
Solution Approach 1:
A control circuit acts as an intermediary between the ultra-capacitor module and the battery, managing their interaction. The control circuit monitors voltage conditions and automatically switches between or combines power sources as needed, simplifying the overall system architecture while maintaining voltage stability during transient events.
Solution Approach 2:
The ultra-capacitor module includes built-in protection circuitry that automatically prevents over-discharging and polarity reversal without requiring external monitoring systems. This self-service capability reduces the complexity of the overall control system while maintaining reliability.
3Power
If ultra-capacitor is used in series with battery, then floating voltage is maintained higher, but risk of over-discharging and polarity reversal increases
Solution Approach 1:
The control circuit performs preliminary assessment of the ultra-capacitor's charge state before allowing it to discharge. It monitors voltage levels and prevents discharge below a safe threshold, avoiding over-discharging and polarity reversal while still maintaining higher floating voltage during normal operation.
Solution Approach 2:
The control circuit continuously monitors the ultra-capacitor module's voltage and current conditions, providing real-time feedback to adjust the discharge rate and prevent dangerous operating conditions. This feedback mechanism maintains higher floating voltage while protecting against over-discharging and polarity reversal.
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 configuration alleviates the burden on SLA batteries during transient current events, ensuring minimum voltage requirements for safety loads like steering and braking are met, and maintains a higher floating voltage compared to using only an SLA battery.
Implementation Method 1
an ultra-capacitor coupled to the battery... The ultra-capacitor's low internal resistance and high power discharge capability takes the burden of supporting transient current events off of the SLA battery
Implementation Method 2
The bypass circuit monitors and prevents the capacitor from over discharging and reversing in polarity... (1) pair of op-amps and a precision voltage reference to monitor the voltage level of the ultra-capacitor
Data Source
AI summary
A vehicle power system includes loads, a battery coupled to the loads, an ultra-capacitor coupled to the battery, and a bypass circuit. The loads, the ultra-capacitor, and the battery are electrically coupled in series. The bypass circuit monitors the ultra-capacitor and prevents the ultra-capacitor from over-discharging and reversing in polarity.