Resonant DC-DC Converter Control for Wide-Range EV Battery Charging
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Solution Overview
Problem
Existing DC/DC converters for electric vehicle charging face inefficiencies under light load conditions and wide output voltage fluctuations, particularly in battery charging applications, leading to low power conversion efficiency and stress on components.
Innovation Solution
A converting circuit comprising a first and second resonant converter, each with fixed switching frequency for constant voltage control, and a phase shift full-bridge converter, with phase-shifted control signals to manage voltage and current, ensuring zero-voltage switching and minimizing stress across a wide voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional DC/DC converter is used for battery charging, then the charging function is provided, but power conversion efficiency is low under light load conditions and wide output voltage fluctuations
Solution Approach 1:
The DC/DC converter is divided into two independent conversion channels: a first resonant converter for constant voltage control and a second resonant converter for constant current control. Each channel operates independently with its own switching elements and control circuitry, allowing optimized efficiency across different load conditions without requiring a single converter to handle the entire operating range.
Solution Approach 2:
The controller dynamically switches between constant voltage and constant current control modes based on real-time monitoring of battery voltage and current. The system transitions from constant voltage control when voltage thresholds are not met to constant current control when thresholds are exceeded, adapting to changing load conditions and maintaining high efficiency throughout the charging process.
2Reliability
If conventional voltage control methods are used, then voltage regulation is achieved, but component stress increases under wide voltage range conditions
Solution Approach 1:
The voltage control function is segmented between two resonant converters, each handling a specific portion of the voltage range. The first resonant converter handles constant voltage control for a first voltage range, while the second resonant converter handles constant current control for a second voltage range, preventing any single converter from experiencing excessive stress across the entire wide voltage range.
Solution Approach 2:
The system changes control parameters dynamically by switching between constant voltage control mode and constant current control mode based on battery voltage thresholds. This parameter change allows the system to maintain optimal operating conditions and reduce component stress by keeping each converter operating within its designed voltage range.
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 enhances charging efficiency by maintaining optimal control across varying load conditions, reducing losses and stress, and maximizing power conversion efficiency in both charging and discharging phases.
Implementation Method 1
a first resonant converter including at least two first switching elements and configured to output a first output voltage
Implementation Method 2
a phase shift full-bridge converter configured to transmit, to an output terminal, at least a portion of a direct current (DC) voltage that is transmitted from an input terminal due to a phase shift between the first control signal and the second control signal
Data Source
AI summary
Disclosed is a converting circuit for an on-board charging device. The converting circuit for the on-board charging device includes a first resonant converter; a second resonant converter; a phase shift full-bridge converter; and a controller.