SEPIC Converter for Electric Vehicle On-Board Electronics
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Solution Overview
Problem
Existing charging devices for electric vehicles require heavy and bulky transformers or unsafe step-down converters, posing safety hazards and inefficiencies in voltage conversion for on-board electronics.
Innovation Solution
A charging device incorporating a SEPIC converter with capacitive isolation, which converts high voltage from the traction battery to a lower voltage required by on-board electronics, ensuring safety and efficiency without bulky equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer is used as a DC-DC converter, then galvanic isolation and safety are improved, but the device becomes heavy and bulky
Solution Approach 1:
The patent changes the fundamental operating parameters of the DC-DC converter by using a resonant converter topology operating in discontinuous conduction mode. This allows achieving galvanic isolation and safety without the heavy transformer core, as the resonant inductors and capacitors provide the necessary isolation properties with much lower weight and volume.
Solution Approach 2:
The patent replaces the traditional magnetic transformer-based isolation mechanism with an electronic resonant circuit-based isolation mechanism. The resonant converter uses L-C resonance to achieve galvanic isolation without relying on a heavy magnetic transformer, thus substituting a mechanical/magnetic system with an electronic one.
2Weight of stationary object
If a step-down (buck) converter is used as a DC-DC converter, then the device becomes lighter and more compact, but safety is compromised due to lack of galvanic isolation
Solution Approach 1:
The patent introduces resonant inductors and capacitors as intermediary elements between the input and output of the DC-DC converter. These resonant components create a galvanic barrier that provides safety isolation, while the overall converter topology remains compact and lightweight compared to traditional transformer-based solutions.
Solution Approach 2:
The patent employs a dynamic resonant converter topology that operates in discontinuous conduction mode, allowing the circuit to dynamically achieve galvanic isolation during operation. The switching elements and resonant components work together dynamically to provide safety isolation without requiring a heavy static transformer structure.
3Weight of stationary object
If both DC-DC converter and charging means are incorporated into the same charging device, then space and weight are saved, but device complexity increases
Solution Approach 1:
The patent designs a universal charging device that can operate in multiple modes: it can function as both a DC-DC converter for voltage conversion and as a battery charging device. The resonant converter topology serves dual purposes, enabling the system to adapt to different operating conditions without requiring separate dedicated circuits for each function.
Solution Approach 2:
The patent merges the DC-DC conversion function and the battery charging function into a single integrated charging device. By combining these two functions into one unified resonant converter system, the patent reduces overall device weight and space while managing complexity through shared control and circuitry.
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 SEPIC converter provides reliable, compact, and safe voltage conversion, addressing safety concerns and space constraints in electric vehicle charging systems.
Implementation Method 1
the second conversion module comprising a SEPIC converter... the SEPIC converter has an input, an output and a capacitor providing capacitive isolation between the input and the output
Data Source
AI summary
The invention relates to a charger (2) for a motor driven apparatus (8), the motor driven apparatus (8) including a battery (5) and pieces of equipment (7a, 7b, 7c), said charger (2) including: a first conversion module (3) for converting an alternating input current into a direct current having a first voltage; a second conversion module (4) for converting a direct current having a first voltage into a direct current having a second voltage that is lower than the first voltage; a switching module (6) connected to the first conversion module (3), and to the second conversion module (4), suitable for being connected to the battery (5); the switching module (6) being suitable for: in a charging mode, supplying power to the second conversion module (4) and the battery (5) via the first conversion module (3); in a use mode, supplying power to the second conversion module (4) via the battery (5); the second conversion module (4) being suitable for supplying power to the pieces of equipment (7a, 7b, 7c), and the second conversion module (4) including an SEPIC converter. The invention also relates to the motor driven apparatus including said device and to an electrical power supply method that uses said device.