Bi-directional DC/DC Converter with Dynamic Control Mode Switching
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Solution Overview
Problem
Resonance type bi-directional DC/DC converters face inefficiencies and limited voltage control, particularly at light or no load conditions, making them unsuitable for devices with a wide range of input/output voltages such as battery chargers.
Innovation Solution
A bi-directional DC/DC converter that employs fixed frequency control and frequency modulation control, with change-over mechanisms based on detected voltage and current values, to expand the voltage range by switching between control modes and maintain efficient operation across varying loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resonance type bi-directional DC/DC converter uses fixed frequency control, then voltage range is limited, but device complexity is reduced
Solution Approach 1:
The patent implements dynamic control mode switching between fixed frequency control and frequency modulation control based on load conditions. The controller automatically transitions between control modes to expand the voltage delivery range while maintaining system stability, directly resolving the contradiction between voltage range and device complexity
Solution Approach 2:
The patent changes the operating frequency parameter dynamically by switching between fixed frequency mode and frequency modulation mode. This parameter change enables the converter to deliver a wider voltage range, particularly improving light load performance without requiring additional hardware components
2Adaptability or versatility
If resonance type bi-directional DC/DC converter operates at light or no load, then efficiency is reduced, but operational flexibility is improved
Solution Approach 1:
The patent dynamically adjusts the switching frequency parameter based on load conditions. At light or no load, the frequency modulation control mode is activated to optimize efficiency by operating at frequencies that minimize losses, while maintaining the ability to adapt to various load conditions
Solution Approach 2:
The controller monitors load conditions and provides feedback to automatically switch between control modes. This feedback mechanism ensures efficient operation at light loads by activating frequency modulation control when needed, while preserving operational flexibility across the full load 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
This approach allows for expanded voltage range delivery, enhancing the converter's applicability to devices with wide input/output voltage requirements, including battery chargers, by optimizing semiconductor switching element operation and reducing losses.
Implementation Method 1
an LC resonance circuit(s) connected between a primary side and a secondary side through an isolation transformer
Data Source
Figure 1
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AI summary
A bi-directional DC/DC converter comprises: bridge circuits 18 and 19 connected to DC voltage sources 1 and 2, an isolation transformer 17 isolating respective AC sides of the bridge circuits, an LC resonance circuit disposed between the AC side of the bridge circuit 18 and the isolation transformer and/or an LC resonance circuit disposed between the AC side of the bridge circuit 19 and the isolation transformer, detection circuits 20 and 21 for detecting voltages and currents of the DC voltage sources 1 and 2, control circuits 22 and 23 for controlling semiconductor switching elements 5 through 12. Each of the control circuits 22 and 23 comprises respective control means 22a and 23a for fixed frequency control at around the resonance frequency fr and respective control means 22b and 23b for performing frequency modulation control at a frequency lower than the resonance frequency fr. The control circuit 22, in the power flow from the second DC voltage source 1 to the second DC voltage source 2, changes over between the fixed frequency control and the frequency modulation control according to the magnitude of the control variable 22c, and the control circuit 23, in the power flow from the second DC voltage source 2 to the second DC voltage source 1, changes over between the fixed frequency control and the frequency modulation control according to the magnitude of the control variable 23c. Thus, the bi-directional DC/DC converter can be applied to devices with a wide range of input and output voltages.