Isolated DC-DC Converter Switching to Prevent Inrush Current
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Solution Overview
Problem
Existing power conversion devices face challenges in safely switching between parallel and series connections during operation, leading to potential voltage spikes and inrush currents, which can cause system errors or shutdowns, especially when handling high voltages and currents.
Innovation Solution
A power conversion device with multiple isolated DC-DC converters and a control unit that manages the switching process by controlling the connection state of these converters, ensuring one remains operational while the other regenerates its energy storage before reconnecting, thereby preventing sudden voltage changes and inrush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output connection is switched from parallel to series during operation, then the output voltage can be increased, but a sudden voltage application may cause inrush current and system errors
Solution Approach 1:
The control unit discharges the output capacitor of the stopped DC-DC converter before switching the connection, preventing sudden voltage application. This preliminary discharge action eliminates the risk of inrush current and system errors when transitioning from parallel to series connection
Solution Approach 2:
The system dynamically adjusts the connection configuration between parallel and series based on operational requirements. The control unit manages the switching process by coordinating the operation states of multiple DC-DC converters and controlling the discharge timing, enabling flexible adaptation while maintaining system stability
2Speed
If simple switching between parallel and series connections is performed, then the connection state can be changed quickly, but inrush current may flow causing error issuance and system shutdown
Solution Approach 1:
The control unit performs preliminary discharge of the output capacitor before connection switching occurs. This preparatory action removes the harmful voltage potential that would otherwise cause inrush current, enabling safe switching without system shutdown
Solution Approach 2:
The output capacitor serves as an intermediary energy storage element that is deliberately discharged before switching. This intermediary mechanism absorbs and dissipates the energy that would otherwise cause inrush current, protecting the system during transition
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
Enables safe and efficient switching between parallel and series connections without disrupting the load, maintaining operational continuity and preventing inrush currents, thus enhancing system stability and reliability.
Implementation Method 1
outputs each including a direct current capacitor
Implementation Method 2
regenerates a stored energy of the direct current capacitor of the isolated DC-DC converter that has been stopped to the isolated DC-DC converter continuing operation
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A power conversion device includes a control circuit, wherein when switching outputs of a first DC-DC converter and a second DC-DC converter from a parallel connection to a series connection, the control circuit causes at least one of the first and second DC-DC converters to continue the operation, cuts off the output of the isolated DC-DC converter that has been stopped using the switches, thereafter causes the isolated DC-DC converter that has been stopped to regenerate the stored energy of an output direct current capacitor to the input side, and when the voltage between the terminals of the output direct current capacitor of the isolated DC-DC converter that has been stopped becomes equal to or less than a predetermined value, causes the output of the isolated DC-DC converter that has been stopped to be connected in series, and restarts the operation of the isolated DC-DC converter that has been stopped.