DC-DC Voltage Converter Bidirectional Control for Hybrid Vehicle Energy Transfer
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Solution Overview
Problem
In electric drive systems, particularly in hybrid and electric vehicles, the high voltage boost ratio between energy sources and DC links leads to inefficiencies and uncontrollable current events when the energy source voltage exceeds the desired DC link voltage, necessitating a controlled energy transfer mechanism.
Innovation Solution
A system comprising a first energy source, a DC link, a first and second DC-to-DC voltage converter, and a controller that compares voltage levels to control the energy transfer, ensuring the DC voltage output from the first energy source is below the DC link voltage, thereby preventing uncontrolled current and enhancing system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bi-directional boost converter is used to decouple the energy source from the DC link and boost voltage from the energy source to a higher level, then the voltage mismatch between energy source and DC link is resolved, but system efficiency decreases due to high voltage boost ratio
Solution Approach 1:
The patent introduces a DC-to-DC voltage converter as an intermediary device between the energy source and the DC link. This converter acts as a mediator that can bidirectionally transfer energy and adjust voltage levels, eliminating the need for high-ratio boost conversion while maintaining voltage compatibility and reducing energy losses.
Solution Approach 2:
The patent changes the operating parameters by using a DC-to-DC voltage converter that can operate in both buck and boost modes. This allows the system to dynamically adjust voltage levels based on the relative voltage between the energy source and DC link, optimizing efficiency by avoiding fixed high-ratio boost conversion.
2Loss of energy
If the energy source voltage is set above the DC link voltage to improve efficiency, then voltage boost ratio is reduced, but uncontrollable current events occur when energy source voltage exceeds DC link voltage
Solution Approach 1:
The patent implements a dynamic control system using a DC-to-DC voltage converter that can bidirectionally transfer energy. The converter dynamically adjusts its operation mode (buck or boost) based on the real-time voltage comparison between the energy source and DC link, ensuring controlled current flow while maintaining optimal efficiency.
Solution Approach 2:
The patent employs a feedback mechanism where the controller continuously monitors the voltage levels of both the energy source and DC link. Based on this feedback, the controller determines the appropriate operating mode of the DC-to-DC voltage converter, ensuring that current flow remains controlled and preventing uncontrolled current events.
3Device complexity
If direct connection between energy source and DC link is used, then system complexity is reduced, but voltage mismatch causes energy transfer inefficiency
Solution Approach 1:
The patent uses a DC-to-DC voltage converter that serves multiple functions: it can operate in buck mode when energy source voltage exceeds DC link voltage, in boost mode when DC link voltage exceeds energy source voltage, and provides controlled energy transfer. This multi-functionality replaces what would otherwise require multiple separate components, managing complexity while ensuring efficiency.
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 solution allows for controlled energy transfer, reducing power losses and improving overall system efficiency by managing voltage levels between the energy source and the DC link, preventing uncontrolled current events and optimizing energy distribution.
Implementation Method 1
a first DC-to-DC voltage converter coupled to the DC link and configured to supply the DC load voltage to the DC link, and a second DC-to-DC voltage converter coupled to the first energy source
Data Source
AI summary
A system for transferring energy from an energy source includes a first energy source 12, a DC link coupled to a DC load, a first DC-to-DC voltage converter 14 coupled to the DC link, and a second DC-to-DC voltage converter 20,22 coupled to the first energy source 12. A controller 84 is coupled to the first 14 and second 20,22 DC-to-DC voltage converters and configured to determine a voltage level of the first energy source 12 and of the DC link. If the voltage level of the DC link is less than the voltage level of the first energy source 12, the controller 84 controls the second DC-to-DC voltage converter to draw energy from the first energy source to cause the DC voltage output from the first energy source and supplied to the first DC-to-DC voltage converter to be below the DC load voltage supplied to the DC link via the first DC-to-DC voltage converter.