Pre-Charging Circuit for DC-DC Converters in Hybrid Vehicles
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Solution Overview
Problem
In hybrid vehicles, the pre-charging process of capacitors in DC-DC converters leads to magnetizing inrush current, which is dangerous for security MOSFETs due to the limitations of their safe operating area, particularly during the initial stage of charging from 0 V to 14 V.
Innovation Solution
A pre-charging circuit with a constant current source circuit, including a half-wave rectification circuit and a constant current source circuit with resistors and transistors, limits the maximum current during charging, using an auxiliary power supply generating means and security MOSFETs to safely manage the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If security MOSFETs are used to protect against inrush current, then MOSFET safety is improved, but circuit complexity and cost increase
Solution Approach 1:
The patent introduces a constant current source circuit as an intermediary component between the power supply and the capacitors. This intermediary actively controls the charging current to remain within the safe operating area of security MOSFETs, providing protection without requiring complex additional circuitry or expensive specialized components.
Solution Approach 2:
The patent employs standard, readily available electronic components (resistors, transistors, diodes, capacitors) to construct the constant current source and pre-charging circuit. These conventional components are cost-effective and widely available, avoiding the need for expensive specialized protection devices while achieving reliable MOSFET safety through proper current control.
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 reduces the magnetizing inrush current during the initial charging stage, ensuring the safe operation of security MOSFETs and allowing for a lower-cost, longer charging time pre-charging circuit.
Implementation Method 1
the auxiliary power supply generating means comprises a half-wave rectification circuit
Implementation Method 2
A pre-charging circuit with a constant current source circuit, including a half-wave rectification circuit and a constant current source circuit with resistors and transistors, limits the maximum current during charging
Data Source
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AI summary
The embodiments of this disclosure relate to a pre-charging circuit for a direct current (DC)-DC converter, a DC-DC converter which converts a voltage between a first power supply and a second power supply, and a hybrid vehicle comprising the DC-DC converter. The pre-charging circuit comprises: an auxiliary power supply generating means, which is connected with a first power supply, and configured to generate an auxiliary power supply; a constant current source circuit configured to supply a charging current to the outside based on the auxiliary power supply; and a switch part connected between the auxiliary power supply generating means and the constant current source circuit, wherein an output terminal of the constant current source circuit is connected to a security device of the DC-DC converter.