Bidirectional Charger Backup for Vehicle Power Stability
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Solution Overview
Problem
Conventional in-vehicle power supply systems face instability and limited travel distance in limp home mode due to failures in bidirectional DC/DC converters or low-voltage batteries, leading to unstable auxiliary device operation.
Innovation Solution
The system includes a high-voltage battery, low-voltage battery, main power converter, bidirectional charger, and control device to stabilize power distribution by stepping down high-voltage power to low-voltage systems when failures occur, and uses an equipotential connection to stabilize low-voltage system voltage when the low-voltage battery fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bidirectional DC/DC converter fails, then the low-voltage battery can drive the auxiliary device, but the vehicle can travel in limp home mode for only a short distance
Solution Approach 1:
The patent introduces a charger power converter as an intermediary component within the bidirectional charger to provide backup power conversion capability. When the main power converter fails, the charger power converter acts as a mediator to step down high-voltage power and supply it to the low-voltage system, enabling extended limp home mode operation beyond what the low-voltage battery alone can provide.
2Reliability
If the low-voltage battery fails, then the bidirectional DC/DC converter can supply electric power to the low-voltage system, but the voltage of the low-voltage system power line may become unstable
Solution Approach 1:
The bidirectional charger is designed with multi-functionality, incorporating both charging capability and power conversion capability. The charger power converter can serve dual purposes: charging the high-voltage battery from external power sources and stepping down high-voltage power to supply the low-voltage system when the main power converter or low-voltage battery fails, thereby maintaining voltage stability through its voltage regulation functions.
3Device complexity
If using only the low-voltage battery to power auxiliary devices after main power converter failure, then the system is simple, but the travel distance is limited
Solution Approach 1:
The charger power converter is pre-configured within the bidirectional charger system, ready to provide power conversion functions when needed. This preliminary preparation of backup power conversion capability eliminates the need for complex additional equipment while extending travel distance, as the charger power converter can immediately take over power conversion duties upon main power converter failure.
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
Enables stable travel over a longer distance in limp home mode by maintaining power stability to auxiliary devices even with converter or battery failures, ensuring reliable operation.
Implementation Method 1
the charger power converter is connected to the low-voltage system power line, and when detecting a failure in the main power converter, the control device controls the charger power converter so as to step down the electric power of the high-voltage system power line by the charger power converter and supply the stepped down electric power to the low-voltage system power line
Data Source
AI summary
The power supply system includes a high-voltage battery connected to the drive device by a high-voltage system power line, a low-voltage battery connected to the auxiliary device by a low-voltage system power line, a main power converter connected to the high-voltage system power line and the low-voltage system power line, and a bidirectional charger connected to the external power side and the high-voltage system power line for charging the high-voltage battery and supplying the voltage of the high-voltage battery to an external electric load. When a failure is detected in the main power converter, the charger power converter is controlled so as to step down the power of the high-voltage system power line by the charger power converter and supply the power to the low-voltage system power line.