Dual-Voltage In-Vehicle Power Supply With Capacitor Load Support
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Solution Overview
Problem
The existing in-vehicle power supply systems face challenges in reducing the cost and diameter of power supply lines while minimizing electric power loss, particularly when dealing with large electric power loads that require higher voltages, leading to increased costs and potential voltage fluctuations.
Innovation Solution
The proposed system employs a power supply control unit with a DC/DC converter to step down high-voltage power to 12V, and a capacitor to supplement power to large electric power loads, reducing current demand and voltage fluctuations, thereby minimizing wire diameter and power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a thick electric wire is used for power supply lines to large electric power loads, then electric power loss is reduced, but cost of the entire vehicle increases
Solution Approach 1:
The power supply system is segmented into multiple voltage levels (12V and 48V) with separate power supply lines for each voltage level. Large electric power loads are supplied through the 48V power supply line, while small electric power loads are supplied through the 12V power supply line. This segmentation allows the use of thinner wires for the 48V line compared to what would be required for a 12V line carrying the same power, reducing overall material cost while maintaining low power loss.
Solution Approach 2:
The system changes the voltage parameter from a single 12V level to dual levels (12V and 48V). By stepping up the voltage to 48V for large power loads, the current is reduced for the same power transmission (P=VI), which allows the use of thinner wire gauges while maintaining acceptable voltage drop and power loss levels, thereby reducing manufacturing cost.
2Ease of manufacture
If a single in-vehicle battery is mounted, then cost is reduced, but power supply capability becomes insufficient in power supply systems not directly connected to the battery
Solution Approach 1:
A DC/DC converter is introduced as an intermediary device between the single 12V battery and the 48V power supply line. The DC/DC converter converts 12V from the battery to 48V, enabling the 48V power supply line to be powered indirectly from the single battery. This intermediary allows the system to maintain dual-voltage capability without requiring a separate 48V battery, thus reducing cost while maintaining power supply capability.
3Quantity of substance
If power supply voltage is stepped up to 48V for large electric power loads, then current demand is reduced, but device complexity increases due to additional DC/DC converters
Solution Approach 1:
The DC/DC converter functionality is implemented locally at specific points in the system where voltage conversion is needed, rather than requiring centralized conversion. Zone ECUs with integrated DC/DC converters can independently convert 12V to 48V for local large power loads, reducing the need for high-current 12V wiring throughout the entire vehicle and allowing for optimized local power management.
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 solution effectively reduces the diameter of power supply lines and minimizes electric power loss while maintaining stable voltage, thereby preventing cost increases and ensuring efficient power delivery to both small and large electric power loads.
Implementation Method 1
a power supply control unit 15A with a DC/DC converter 16 to step down power supply power of a high voltage into power supply power of 12V
Implementation Method 2
a capacitor 20 to supplement power to large electric power loads 14
Data Source
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AI summary
An auxiliary device system battery and a small electric power load are connected to a first power supply line, and power supply power stepped up by a DC/DC converter in a zone ECU is supplied to a second power supply line. A large electric power load and a capacitor are connected to the second power supply line, and when the large electric power load is driven, the capacitor is connected to supply necessary power supply power, and voltage fluctuation is prevented. When an ignition is OFF, a switch circuit is closed, a dark current is supplied from the capacitor, and electric charge is discharged to prevent deterioration. Alternatively, the auxiliary device system battery is connected to a second power supply line side, and a dark current is supplied to a first power supply line side when the ignition is OFF using a capacitor or a dedicated circuit.