Dual Active Bridge Startup Control for Inrush Current Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DAB power conversion devices require complex circuit structures due to variable gate driver voltage needs during start-up and normal operations, complicating the startup process.
Innovation Solution
A DAB power conversion device with a controller that performs bidirectional DC-to-DC conversion using primary-side and secondary-side bridge circuits and an inductance element, where one side's DC terminals are charged while the other side's bridge circuit operates in diode rectifying mode, with controlled voltage pulse width to manage inrush current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable gate driver voltage is used during start-up and normal operations, then inrush current is reduced, but circuit structure becomes complex
Solution Approach 1:
The patent changes the voltage pulse width parameter of the AC voltage output during start-up control instead of changing gate driver voltage. By adjusting the pulse width of the AC voltage from the primary-side bridge circuit, the inrush current to the uncharged DC terminal is controlled without requiring variable gate driver voltage, thus avoiding additional circuit complexity while still achieving reliable inrush current management
Solution Approach 2:
The patent extracts the voltage transformation function from the gate driver circuit and relocates it to the bridge circuit's AC voltage output. By controlling the pulse width of the AC voltage at the bridge circuit level, the need for variable gate driver voltage is eliminated, simplifying the overall circuit structure while maintaining effective inrush current control
2Loss of time
If both DC terminals are charged simultaneously, then startup time is reduced, but inrush current increases
Solution Approach 1:
The patent segments the charging process into two distinct phases: first charging one DC terminal while the other remains uncharged, then switching to charge the second terminal. This sequential segmentation prevents simultaneous charging that would cause excessive inrush current, while the entire process remains under controlled timing to minimize total startup time
Solution Approach 2:
The patent performs preliminary charging of one DC terminal before initiating charging of the second terminal. By pre-charging one side and using its AC voltage output to charge the other side in a controlled manner, the system prepares the power conversion path in advance, enabling efficient sequential charging that limits inrush current while maintaining quick startup
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 quick and safe startup by managing inrush current and voltage differences between DC terminals, simplifying the circuit structure and improving startup efficiency.
Implementation Method 1
The primary-side bridge circuit includes semiconductor switching elements and performs bidirectional DC-to-AC power conversion between the primary-side DC terminals and primary-side alternating-current (AC) terminals
Implementation Method 2
The inductance element is connected between the primary-side AC terminals and the secondary-side AC terminals
Implementation Method 3
The primary-side bridge circuit performs bidirectional DC-to-AC power conversion between the primary-side DC terminals and primary-side alternating-current (AC) terminals
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
In a start-up control in which primary-side direct-current (DC) terminals (5a, 6a) and secondary-side DC terminals (5b, 6b) are charged by an external power supply outside a power conversion device (100), initially, one-side DC terminals are charged by the external power supply while switching operations of the primary-side bridge circuit (30a) and the secondary-side bridge circuit (30b) are stopped. Subsequently, a bridge circuit that is connected to the DC terminals not charged by the external power supply stops the switching operation and operates in a diode rectifying mode, while a bridge circuit that is connected to the DC terminals charged by the external power supply performs the switching operation and outputs an AC voltage whose voltage pulse width has been subjected to a variable control so that the voltage pulse width is smaller for a greater voltage difference of the charged DC terminals from the uncharged DC terminals.