Multi-Port DC-DC Converter With LCL-T Resonance for Light-Load ZVS
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Solution Overview
Problem
Existing multiple-port bidirectional DC-DC converters face challenges with high switching frequency losses and loss of zero voltage switching (ZVS) at light loads, particularly in configurations using LCL-T resonant circuits and series resonant converters, which complicates design and control.
Innovation Solution
A multiple-port bidirectional DC-DC converter with a LCL-T resonant circuit at one port and a series resonant converter or dual-active bridge (DAB) at another port, operating at fixed switching frequency, allowing for zero voltage switching (ZVS) even at lighter loads without high frequency operation, and enabling dynamic configuration based on application and load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high switching frequency is used to improve power conversion efficiency, then power transfer efficiency is improved, but switching losses increase and zero voltage switching (ZVS) is lost at light loads
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the converter operates at variable frequency rather than fixed frequency. The control system dynamically adapts the switching frequency based on load conditions, enabling operation at optimal frequencies that maintain ZVS at light loads while achieving high efficiency at full load, thus resolving the contradiction between efficiency and switching losses
Solution Approach 2:
The patent changes the operating parameter of switching frequency from a fixed value to a variable parameter that can be adjusted according to load demands. This parameter change enables the system to optimize performance across different operating conditions, maintaining soft switching characteristics at light loads while achieving high power conversion efficiency at full load
2Adaptability or versatility
If LCL-T resonant circuit configuration is used to achieve bidirectional power flow, then power flow flexibility is improved, but design complexity and control difficulty increase
Solution Approach 1:
The patent employs a unified control strategy that manages multiple operating modes (bidirectional power flow, single-direction power flow, different load conditions) through a single control framework. This universal control approach simplifies the overall system design by eliminating the need for separate control circuits for different modes, thus reducing design complexity while maintaining full bidirectional power flow capability
Solution Approach 2:
The patent implements dynamic mode switching capability where the converter can seamlessly transition between different operating modes (bidirectional, unidirectional, different load conditions) based on real-time system requirements. This dynamic adaptability is achieved through intelligent control that automatically selects optimal operating modes, simplifying the control architecture while maintaining versatility
3Ease of operation
If fixed switching frequency operation is used to simplify control, then control complexity is reduced, but ability to maintain ZVS at light loads is worsened
Solution Approach 1:
The patent changes the switching frequency from a fixed parameter to a dynamically adjustable parameter. The control system modifies the switching frequency based on real-time load conditions, ensuring that ZVS characteristics are maintained at light loads while achieving optimal efficiency at full load. This parameter adaptation resolves the contradiction between control simplicity and ZVS maintenance
4Adaptability or versatility
If multiple ports are integrated to enable single DC source to supply multiple loads, then system integration is improved, but power distribution control complexity increases
Solution Approach 1:
The patent implements a universal control architecture that manages power distribution across multiple ports through a single integrated control system. This unified approach enables the converter to handle various power distribution scenarios (single-port, dual-port, multi-port operation) using the same control framework, thereby simplifying control complexity while maintaining high system integration and versatility
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
Simplifies the design of magnetic components and control, maintains ZVS across varying loads, and reduces switching frequency-related losses, enhancing reliability and efficiency in applications like DC micro-grids and electric vehicles.
Implementation Method 1
a transformer that passes the AC signal by electromagnetic induction to a secondary side of the transformer
Implementation Method 2
a resonant circuit including a first inductor (L 1 ), a capacitor (C), and a second inductor (L 2 ) arranged in a 'T' configuration (LCL-T)
Data Source
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AI summary
A direct current (DC)-DC converter (100) includes a first port 102() at a primary side of a transformer (103) including a primary-side converter (120) with primary-side switches (125) and a second port (104-1) at a secondary side including a second port converter (140-1) with second-port switches (145-1) and a resonant circuit (310) including a first inductor (L1), a capacitor (C), a second inductor (L2) in LCL-T arrangement, a third port (104-2) at the secondary side including a third port converter (140-2) with third-port switches (145-2), and a controller (110) configured to control the primary-side switches (125), the second-port switches (145-1), and the third-port switches (145-2) at fixed-frequency for operation in a first mode, in which the first port (102) supplies power to the second port (104-1) and the third port (104-2), in a second mode, in which the second port (104-1) supplies power to the first port (102) and the third port (104-2), or in a third mode, in which the second port (104-1) supplies power to the third port (104-2) while the first port (102) is disconnected.