In-Vehicle Charger SiC Diode Surge Suppression
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Solution Overview
Problem
Existing in-vehicle chargers for electric vehicles face challenges in suppressing diode recovery surge voltage, leading to increased losses, heat generation, and cost due to the use of RCD snubber circuits, and high-voltage components in synchronous rectifier circuits, which complicates the circuit and increases size and cost.
Innovation Solution
The use of Si diodes as rectifying diodes and a high-voltage SiC Schottky barrier diode as a free-wheeling diode between the rectifier circuit and smoothing reactor in an isolated DC/DC converter, allowing for simpler and cost-effective suppression of diode recovery surge voltage without the need for a snubber circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an RCD snubber circuit is used to suppress surge voltage, then surge voltage is suppressed, but loss and heat generation increase and device complexity increases
Solution Approach 1:
The patent extracts and eliminates the RCD snubber circuit from the in-vehicle charger design. By removing this additional circuit component, the invention achieves surge voltage suppression through the inherent characteristics of the isolated DC/DC converter circuit itself, thereby reducing energy loss and heat generation while avoiding the complexity of additional snubber components.
2Object-affected harmful factors
If synchronous rectifier circuit with high-voltage components is used, then surge voltage is suppressed, but device complexity and cost increase
Solution Approach 1:
The patent removes the synchronous rectifier circuit with high-voltage components from the design. Instead, it utilizes the natural surge voltage suppression capability of the isolated DC/DC converter circuit, thereby simplifying the overall circuit structure and reducing component requirements while maintaining effective surge voltage suppression.
3Volume of moving object
If higher switching frequency is used to reduce size, then magnetic component size is reduced, but diode recovery loss and surge voltage increase
Solution Approach 1:
The patent converts the potentially harmful effects of high-frequency switching (diode recovery loss and surge voltage) into beneficial outcomes. By optimizing the isolated DC/DC converter circuit design, the invention utilizes the high switching frequency to reduce magnetic component size while the circuit's inherent characteristics naturally suppress surge voltage and minimize diode recovery losses, turning what would be problematic side effects into acceptable or even advantageous features.
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 effectively suppresses diode recovery surge voltage, reducing the need for additional components and cooling, thus maintaining efficiency and reducing the overall cost and size of the in-vehicle charger.
Implementation Method 1
as a free-wheeling diode, a high-voltage Schottky barrier diode made of a wide bandgap semiconductor is used
Data Source
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AI summary
A Si diode is used as a rectifying diode on a transformer secondary side of an isolated DC/DC converter, and a high-voltage Schottky barrier diode made of a wide bandgap semiconductor is used as a free-wheeling diode arranged between a rectifier circuit and a smoothing reactor. Thus, there may be provided an in-vehicle charger capable of suppressing a diode recovery surge voltage with a circuit configuration that is simpler and suppressed in cost increase as compared to a case where a related-art synchronous rectifier circuit system is employed.