Vehicle Pre-Charge Backup Power via High-Voltage Circuit
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Solution Overview
Problem
The existing electric power systems for vehicles face challenges in quickly finishing the pre-charge of condensers in the high-voltage circuit, particularly when the low-voltage battery's output voltage decreases or connection issues occur, leading to potential power supply interruptions during vehicle collisions or battery degeneration.
Innovation Solution
The electric power system incorporates a high-voltage circuit as a backup power supply, utilizing a voltage-reducing device and diodes to ensure continuous power supply to the system control part, and includes a switch to prevent pre-charge hindrance by disconnecting the high-voltage battery during condenser pre-charge, allowing the high-voltage circuit to serve as a backup and maintain power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the high-voltage battery is connected to supply power to the system control part during pre-charge, then the system control part can operate continuously, but the pre-charge of the smoothing condenser is hindered or takes longer to complete
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the high-voltage battery and the system control part. The DC-DC converter steps down the high voltage to a lower voltage suitable for the system control part, allowing power supply during pre-charge without directly connecting the high-voltage battery to the control part. This resolves the contradiction by enabling continuous power supply while allowing the pre-charge process to proceed at normal speed.
2Loss of time
If the low-voltage battery is used as the sole power source for the system control part, then the pre-charge can proceed quickly, but the system may experience power supply interruptions during collisions or battery degeneration
Solution Approach 1:
The system changes the voltage parameter by introducing a high-voltage power supply path with a DC-DC converter. This allows the system to operate with either low-voltage (during normal operation) or high-voltage (during collisions or battery degeneration) power supply, adapting to different operational conditions and improving reliability without affecting pre-charge speed.
Solution Approach 2:
The high-voltage battery system is prepared in advance as a backup power source. During normal operation, the low-voltage battery supplies power, but the high-voltage system is ready to take over immediately in case of collisions or battery degeneration, providing beforehand cushioning against potential power supply failures.
3Reliability
If a backup power supply system is implemented to ensure continuous power during collisions, then reliability improves, but the system complexity increases
Solution Approach 1:
The high-voltage battery system is designed with multi-functionality: it serves both as the main power source for the motor during normal operation and as a backup power source for the system control part during collisions or battery degeneration. This universal design reduces the need for separate dedicated backup systems, thereby limiting the increase in system complexity.
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 ensures uninterrupted power supply to the system control part, allowing for continuous operation before and after vehicle collisions and preventing pre-charge hindrance, even when the low-voltage battery's output voltage is compromised, by switching to the high-voltage circuit as a backup power source.
Implementation Method 1
a voltage-reducing device (for example, a voltage-reducing device 55 described below) for reducing a voltage of electric power from the high-voltage circuit
Implementation Method 2
on a side of the first system control power line that is closer to a low-voltage battery than a connecting point of the second system control power line, a first diode (for example, a first diode 33 described below) which permits a current from the low-voltage battery to the system control part is arranged
Data Source
AI summary
An electric power system of a vehicle includes: a high-voltage circuit, which includes a high-voltage battery connected to a main circuit; a system ECU, which controls the main circuit; a first system control power line, which connects a low-voltage battery to the system ECU; a second system control power line, which connects the high-voltage circuit to the first system control power line; a voltage-reducing device, which reduces a voltage of the electric power from the high-voltage circuit; a second switch, which is arranged on the second system control power line; and a backup power supply ECU, which turns the second switch off when a pre-charge of smoothing condensers arranged on the main circuit is performed by supplying the electric power of the high-voltage battery.