Series-Parallel DC/DC Switching Circuit for Seamless Mode Transition
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Solution Overview
Problem
Existing bidirectional DC/DC conversion circuits face challenges in realizing fast switching between series and parallel operating modes due to the need for complete disconnection and discharge of output capacitors, which impedes seamless voltage transitions.
Innovation Solution
A series-parallel switching circuit with two bidirectional DC/DC isolation conversion circuits, output filter capacitors, a bleeder circuit, and a soft-start circuit, allowing for unchanged voltage across capacitors during switching, and capacitive pre-charge to maintain safe voltage differences, enabling fast switching without disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete disconnection and discharge of output capacitors is implemented during mode switching, then safety is improved, but switching time increases and seamless operation is hindered
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitors through the soft-start circuit before switching occurs. The capacitors are charged to a voltage close to the input voltage in advance, so that when switching between series and parallel modes, the voltage difference is minimal and no discharge is needed. This eliminates the time-consuming discharge step while maintaining safety.
Solution Approach 2:
The patent introduces a soft-start circuit as an intermediary component that includes a soft-start switch and resistor. This intermediary circuit provides a controlled charging path for the output capacitors, enabling them to reach the appropriate voltage level before the main switching operation. The intermediary circuit acts as a buffer that prepares the system for seamless switching without requiring complete disconnection.
2Adaptability or versatility
If series-parallel switching is implemented for wide voltage gain, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the DC/DC conversion function into two separate bidirectional DC/DC conversion circuits that can be connected in series or parallel. Each circuit handles a portion of the conversion task, and their combination provides wide voltage gain. The segmentation allows independent control and simplifies the overall architecture by making each module self-contained and manageable.
Solution Approach 2:
The patent implements universality by designing bidirectional DC/DC conversion circuits that can operate in multiple modes (series connection for high voltage gain, parallel connection for current sharing). The same circuit topology and components serve multiple functions depending on the connection configuration, eliminating the need for separate circuits for different voltage conversion ratios and reducing overall device complexity.
3Productivity
If fast switching between series and parallel modes is achieved, then productivity is improved, but reliability may deteriorate due to voltage difference sticking risks
Solution Approach 1:
The patent applies preliminary action by pre-charging the output capacitors to a voltage close to the input voltage before switching. This preparation ensures that when switching between modes, the voltage difference between capacitors is minimal, eliminating the risk of voltage difference sticking. The preliminary charging action enables both fast switching and reliable operation by removing the harmful voltage differential that would otherwise cause reliability issues.
Solution Approach 2:
The patent changes the voltage parameter of the output capacitors through controlled pre-charging. By adjusting the capacitor voltage to match the input voltage before switching, the system transitions from a state with potential large voltage differences to a state with minimal voltage differences. This parameter change enables fast switching without compromising reliability, as the capacitors are in a compatible voltage state for seamless mode transition.
Data Source
AI summary
A series-parallel switching circuit for bidirectional power conversion is provided. The series-parallel switching circuit includes a first bidirectional direct current (DC) voltage source and a second bidirectional DC voltage source, a first bidirectional DC/DC isolation conversion circuit and a second bidirectional DC/DC isolation conversion circuit, a series-parallel switching switch, a first output filter capacitor and a second output filter capacitor, a bleeder circuit, and a soft-start circuit. The series-parallel switching switch is configured to connect the first bidirectional DC/DC isolation conversion circuit and the second bidirectional DC/DC isolation conversion circuit in series or in parallel. When the series-parallel switching switch is switched, a voltage across the first output filter capacitor and a voltage across the second output filter capacitor are unchanged.