EV On-Board Charger Circuit for Multi-Source Input Switching
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Solution Overview
Problem
On-board chargers for electric vehicles face inefficiencies due to varying input electricity sources, use of electrolytic capacitors, parasitic currents, and large size, necessitating improved designs that enhance efficiency and compatibility with different power sources while minimizing flux coupling and capacitor disadvantages.
Innovation Solution
The invention incorporates a multi-function circuit with integrated magnetic components, including inductors and transformers with hybrid windings and non-electrolytic film capacitors, allowing seamless switching between single-phase AC, 3-phase AC, and DC sources, and preventing flux coupling through airgaps, while using a buck converter for efficient voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple magnetic components are integrated into one device, then device size is reduced, but flux coupling between components increases
Solution Approach 1:
Airgaps are introduced as intermediary elements between integrated magnetic components to prevent flux coupling. The airgaps act as magnetic insulators that allow the components to be physically integrated while maintaining magnetic isolation, thus resolving the contradiction between compact integration and flux interference.
2Quantity of substance
If electrolytic capacitors are used in the DC-link, then capacitance requirements are met, but device size and reliability deteriorate
Solution Approach 1:
The patent changes the material parameter of the capacitor from electrolytic to film capacitor. Film capacitors provide the required capacitance with smaller size and superior reliability characteristics, thus resolving the contradiction between capacitance requirements and device size/reliability.
3Device complexity
If a single circuit design is used, then device complexity is reduced, but adaptability to different voltage sources deteriorates
Solution Approach 1:
The multi-function circuit is designed to perform multiple functions by switching between different operational modes. The circuit can process single-phase AC, 3-phase AC, and DC inputs using the same magnetic components and control architecture, achieving universality without proportionally increasing complexity.
4Reliability
If different wire types are used for different windings, then electrical performance is improved, but manufacturing complexity increases
Solution Approach 1:
Different wire types (PCB windings, solid wire windings, litz wire windings) are applied to different magnetic components based on their specific electrical performance requirements. This local differentiation optimizes electrical performance while keeping the overall manufacturing process manageable through standardized procedures.
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 enables efficient operation across multiple voltage sources, reduces parasitic currents, eliminates the need for electrolytic capacitors, and achieves a compact design by minimizing flux coupling and optimizing magnetic component integration.
Implementation Method 1
The integrated cores of the magnetic components are separated by different sized airgaps, including zero airgap, to prevent flux coupling
Implementation Method 2
The inputs of voltage to the multi-function circuit are selected by a single pole single throw relay in the multi-function circuit that switches between the variable sources
Implementation Method 3
The magnetic components comprise inductors and transformers, each with integrated cores
Data Source
AI summary
An on board charger with a multi-function circuit is provided for an electric vehicle and similar applications that uses non-electrolytic capacitors and can switch between different electrical input sources such as single-phase AC, 3-phase AC and DC, and which uses different sized airgaps between magnetic components and hybrid windings for its magnetic components.