Hybrid Vehicle Capacitor Power Control for Starting Load Relief
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Solution Overview
Problem
Hybrid vehicles face challenges in managing power supply due to high current loads during starting and e-boost events, requiring complex battery systems that include both 12V and higher voltage batteries or supercapacitors, which increase complexity and battery wear.
Innovation Solution
A power management system that controls connections between a hybrid vehicle's battery and capacitor, using a battery monitoring module and capacitor charge/discharge module to disconnect nonessential loads, recharge capacitors before engine starts, and manage current flow through DC/DC converters, reducing battery size and wear by distributing power loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a full capacity 12V battery (100 Ah) is used in addition to higher voltage battery or supercapacitor, then the battery can supply sufficient current for starting and loads, but the system complexity increases and battery size/cost increases
Solution Approach 1:
The patent divides the power supply function into two segments: the capacitor (supercapacitor) handles high current transient loads during engine starting and e-boost events, while the 12V battery handles steady-state loads and voltage stabilization. This segmentation allows each component to be optimized for its specific function, enabling the use of a smaller 12V battery (less than 100 Ah) while maintaining sufficient total power capability.
Solution Approach 2:
The capacitor is charged in advance during regenerative braking events and engine operation to store energy before it is needed for high-current starting events. The control system monitors capacitor state of charge and prepares the system beforehand, ensuring that when starting current is required, the capacitor is already charged and ready to deliver the necessary current immediately, reducing the burden on the 12V battery.
2Power
If higher voltage batteries (24V, 36V, 48V) or supercapacitors are used, then the power supply capability is improved, but the system complexity increases due to compatibility with legacy 12V systems
Solution Approach 1:
The patent introduces a DC/DC converter as an intermediary device between the higher voltage battery/supercapacitor system and the legacy 12V vehicle systems. This converter performs voltage transformation and isolation, allowing the high-voltage power source to supply power while the 12V systems continue to operate without modification. The DC/DC converter manages the interface complexity, enabling power upgrade while maintaining compatibility with existing 12V components.
Solution Approach 2:
The patent combines multiple power sources (12V battery, higher voltage battery, and/or supercapacitor) into a unified power architecture where they work together through intelligent control. The control system dynamically manages power flow between these sources, allowing them to be merged functionally while maintaining their electrical independence through the DC/DC converter interface, thus achieving enhanced power capability without requiring complete system redesign.
3Power
If the battery supplies high current during starting and e-boost events, then the starting performance is adequate, but the battery wear increases and battery life decreases
Solution Approach 1:
The patent segments the high current starting load between two power sources: the capacitor provides the majority of the peak current during engine cranking and e-boost events due to its high power density and ability to deliver sustained high currents without degradation, while the 12V battery provides voltage support and handles lower current steady-state loads. This segmentation protects the battery from excessive discharge rates and high-stress transient events, thereby extending battery life.
Solution Approach 2:
The capacitor acts as a sacrificial or short-living component in the sense that it is designed to undergo repeated high-stress charge/discharge cycles during starting events without degrading the more expensive and longer-lived battery. The capacitor can be replaced more easily and at lower cost if needed, protecting the investment in the main battery system.
4Quantity of substance
If nonessential loads are disconnected when battery state of charge is low, then battery capacity requirements are reduced, but the vehicle functionality is limited
Solution Approach 1:
The control system performs preliminary action by monitoring the state of charge of both the 12V battery and the capacitor continuously. When regenerative braking events are detected or predicted, the system prepares in advance by directing charge to the capacitor and managing load distribution before the battery state of charge becomes critical. This proactive management ensures that when low battery SOC occurs, essential functions remain available and the transition to capacitor-supported operation is smooth, maintaining vehicle functionality while enabling smaller battery capacity.
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 system reduces battery capacity and size while maintaining performance, improves battery life by limiting discharge rates, and enhances efficiency by moving power from capacitors to batteries during regenerative braking events.
Implementation Method 1
one or more DC/DC converters controlling current flow between the battery, the capacitor, and at least one of a starter of the vehicle and a generator of the vehicle
Data Source
AI summary
A system for discharging or charging a capacitor of a hybrid vehicle according to the present disclosure includes a target state of charge (SOC) module and a capacitor charge/discharge module. The target SOC module determines a target state of charge of the capacitor based on a speed of the vehicle. The capacitor charge/discharge module determines whether a state of charge of a capacitor is greater than a target state of charge. The capacitor charge/discharge module dissipates power from the capacitor to at least one of a battery of the vehicle and an electrical load of the vehicle when the state of charge of the capacitor is greater than the target state of charge.