DC-DC Converter Pre-Charging Circuit for Electric Vehicles
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Solution Overview
Problem
Inrush currents during the startup of the high voltage electrical network in electric or hybrid vehicles can lead to reduced lifespan of electronic components, and existing pre-charging circuits are costly and inefficient.
Innovation Solution
An isolated DC-DC converter with an additional branch and inductive coils that allows energy transfer from the low voltage network to the high voltage network for pre-charging, using switches to control energy flow and inhibit transfer during active operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pre-charging circuit with relays and resistors is implemented to avoid inrush currents, then the lifespan of electronic components is extended, but the device complexity and cost increase
Solution Approach 1:
The patent merges the pre-charging function with the existing DC-DC converter by adding an additional branch to its circuit. This integration eliminates the need for separate pre-charging circuits with relays and resistors, reducing device complexity while maintaining the protective function against inrush currents through the converter's control mechanism
Solution Approach 2:
The DC-DC converter is designed to perform multiple functions: both the standard voltage conversion from high voltage to low voltage networks and the pre-charging of the high voltage network. This multi-functionality is achieved through the additional branch that can operate in reverse mode, allowing the converter to serve dual purposes and eliminate dedicated pre-charging components
2Reliability
If dedicated pre-charging circuits are implemented, then inrush currents are prevented, but energy losses increase
Solution Approach 1:
The DC-DC converter performs pre-charging using its own internal resources and control mechanisms. The additional branch utilizes the converter's existing inductive coils and switching components to generate the pre-charging current, eliminating the need for external pre-charging circuits that would incur additional energy losses in resistors and relays
3Adaptability or versatility
If an additional branch with inductive coil is added to the DC-DC converter, then pre-charging capability is achieved, but the device complexity increases
Solution Approach 1:
The additional branch is integrated into the existing DC-DC converter structure, sharing common components such as the magnetic circuit, switching elements, and control system. This merging approach adds pre-charging capability while minimizing the increase in overall device complexity by reusing existing infrastructure
Solution Approach 2:
The converter's operating mode is made dynamic through the additional branch, which can be activated or deactivated based on system requirements. The branch enables the converter to switch between standard operation and pre-charging modes, providing adaptability without permanently increasing complexity when the pre-charging function is not needed
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 solution effectively pre-charges the high voltage electrical network, preventing inrush currents and extending the lifespan of electronic components while reducing costs by using smaller, less expensive components.
Implementation Method 1
each inductive coil of said first circuit being coupled to an inductive coil of said second circuit to form at least one transformer, such that, according to a first operating mode, the DC-DC converter is configured to transfer energy from the first electrical network to the second electrical network
Data Source
AI summary
The invention relates to an insulated DC-DC converter, in particular for a motor vehicle, comprising—a first circuit, connected to a first electrical grid, and including a primary branch comprising at least one induction coil, —a second circuit, connected to a second electrical grid, and comprising a secondary branch comprising at least one induction coil, each induction coil of the primary branch being coupled with an induction coil of the secondary branch in order to form a transformer. According to the invention, said converter comprises at least one additional branch comprising at least one additional induction coil, said at least one additional branch being connected to the electrical grid, and said at least one additional induction coil being coupled with an induction coil of the secondary branch so that, according to one operating mode, the insulated DC-DC converter transfers energy from the low-voltage vehicle electrical grid to the electrical grid, in particular for pre-charging purposes.