Resonant EV Charger Power Conversion for Wide Voltage Range
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Solution Overview
Problem
Current electric vehicle charging systems have limited input and output voltage ranges and low efficiency, restricting their application and failing to meet new demands such as grid stabilization and bi-directional power transmission.
Innovation Solution
A power conversion device comprising a first and second power converter, a resonant converter with an isolation transformer, and a controller that controls voltage conversions between AC and DC voltages, allowing operation at a predetermined resonant frequency for efficient power transmission and expanding voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional charger or charging system is used, then the system can perform basic charging function, but the input and output voltage ranges are limited and efficiency is low
Solution Approach 1:
The charging system is divided into multiple independent power conversion modules (first power conversion module, second power conversion module, third power conversion module) that can operate independently or in combination. This segmentation allows the system to handle a broader voltage range by selecting appropriate modules for different operating conditions, thereby improving adaptability while maintaining efficiency through optimized module selection.
Solution Approach 2:
The power conversion modules are designed with universal functionality to handle both AC and DC inputs and outputs. The modules can operate in multiple modes (AC-DC conversion, DC-DC conversion) and can be configured in series or parallel, enabling the system to adapt to various voltage ranges and application scenarios while maintaining high efficiency across different operating points.
2Power
If the charging system operates at high power level, then more power can be transmitted, but the voltage range becomes limited and efficiency decreases
Solution Approach 1:
The system dynamically configures power conversion modules based on real-time operating conditions. Modules can be connected in series to achieve higher voltage levels or in parallel for higher current capability. This dynamic reconfiguration allows the system to maintain high power transmission while adapting to different voltage ranges, preventing efficiency degradation that would occur with fixed configurations.
Solution Approach 2:
The system changes operational parameters (connection topology, module activation) based on the required power level and voltage range. By adjusting these parameters dynamically, the system can operate at high power levels when needed while maintaining the appropriate voltage range for each specific application, thereby avoiding the efficiency loss associated with operating outside optimal parameters.
3Adaptability or versatility
If the charging system is designed for unidirectional power transmission, then the structure is simple, but it cannot meet new needs such as grid stabilization and vehicle-to-grid functionality
Solution Approach 1:
The power conversion modules are designed with bidirectional power flow capability, allowing them to function as rectifiers (AC to DC), inverters (DC to AC), or DC-DC converters depending on the operating mode. This universal design enables the system to support multiple functions including charging, grid stabilization, and vehicle-to-grid power transmission without requiring separate dedicated hardware for each function, thus managing complexity while expanding capability.
Solution Approach 2:
The system dynamically switches between different operational modes (charging mode, discharging mode, grid support mode) based on control signals and system state. This dynamic operation allows a single unified structure to perform multiple functions, avoiding the need for complex parallel systems dedicated to each function while maintaining the ability to meet diverse functional requirements.
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 significantly expands the input and output voltage ranges, enhances efficiency, and enables bidirectional power transmission, making the system suitable for various applications including vehicle-to-grid functionality and energy storage.
Implementation Method 1
control the resonant converter to operate at a predetermined resonant frequency to perform conversion between the second DC voltage and a third DC voltage
Implementation Method 2
a resonant converter coupled between the first power converter and the second power converter, the resonant converter comprising an isolation transformer
Data Source
AI summary
Embodiments of the present disclosure provide a power conversion device, an electric vehicle charging system, and a method of controlling the power conversion device. The power conversion device includes a first power converter and a second power converter; a resonant converter coupled between the first power converter and the second power converter; and a controller. The controller being configured to control the first power converter to perform conversion between an AC voltage or a first DC voltage and a second DC voltage. The controller being configured to control the resonant converter to operate at a predetermined resonant frequency to perform conversion between the second DC voltage and a third DC voltage. The controller being configured to control, based on the voltage information, the second power converter to perform conversion between the third DC voltage and a fourth DC voltage.