DC-DC Converter In-Rush Current Limiting Circuit
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Solution Overview
Problem
Existing DC-DC boost switching converters face issues with destructive in-rush currents during power-up when the primary voltage is lower than the secondary voltage multiplied by the transformer turn ratio, leading to potential circuit damage and requiring bulky and costly solutions to manage this current.
Innovation Solution
The proposed solution involves an insulated DC-DC converter apparatus with additional circuit branches and switches that provide a closed path for the inductor current during power-on, using additional switches and diodes to control the current flow, allowing it to bypass the main switches and reduce in-rush current levels, and includes a controller module to manage the switching signals and current limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional DC-DC boost switching converters are used without additional current limiting circuits, then the converter structure remains simple and cost-effective, but destructive in-rush currents occur during power-up when primary voltage is lower than secondary voltage multiplied by transformer turn ratio
Solution Approach 1:
The controller activates the reactive circuit (inductor) before closing the main switches during power-up sequence. This preliminary action stores energy in the reactive circuit's magnetic field, which then limits the in-rush current when the main switches are closed, preventing destructive current spikes without requiring additional complex circuitry
Solution Approach 2:
The reactive circuit (inductor) acts as an intermediary element between the voltage source and the main switches. It mediates the power transfer by storing and releasing energy in controlled amounts, smoothing the current waveform and preventing direct in-rush currents while maintaining the original converter topology
2Reliability
If bulky and costly solutions are implemented to manage in-rush current, then circuit damage is prevented, but the converter apparatus becomes more complex and expensive
Solution Approach 1:
The reactive circuit is designed to automatically limit in-rush current through its inherent energy storage property. The controller simply manages the switching sequence, and the reactive circuit self-regulates the current flow based on its magnetic field characteristics, eliminating the need for additional active protection circuits or complex control mechanisms
Solution Approach 2:
The invention changes the operational parameters of existing components by controlling the timing and sequence of switch activation. By adjusting when the reactive circuit is activated relative to the main switches, the system dynamically controls current characteristics without changing the physical structure or adding costly protection devices
3Productivity
If main switches are closed during power-up when primary voltage is lower than secondary voltage multiplied by turn ratio, then voltage conversion function is achieved, but destructive in-rush currents flow through the reactive circuit
Solution Approach 1:
The controller closes the reactive circuit switch before closing the main switches during power-up. This preliminary action builds up current in the reactive circuit's magnetic field in a controlled manner, and when the main switches subsequently close, the stored magnetic energy limits the in-rush current while still enabling voltage conversion
Solution Approach 2:
The reactive circuit provides beforehand cushioning by storing energy in its magnetic field before the main switches close. This pre-stored energy acts as a buffer that absorbs and limits the in-rush current冲击, protecting the circuit while allowing the voltage conversion function to proceed
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 effectively limits in-rush currents during power-up, prevents destructive voltage surges, and reduces the complexity and cost of the converter apparatus, while also addressing transformer saturation issues during normal operation, making it suitable for both monodirectional and bidirectional converters.
Implementation Method 1
a transformer in turn comprising a primary winding and a secondary winding with central tap
Implementation Method 2
a reactive circuit connected in series between said central tap and node to which a continuous input voltage to convert is applied
Data Source
Figure 1~2
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AI summary
A DC-DC boost insulated switching converter apparatus is described, including a transformer (11) in turn including a first winding (12) and a second winding (13) with a lesser number of coils with respect to the first winding (12) and having a central tap (13c), an energy storage reactive circuit (15), in particular an inductor, connected in series between said central tap (13c) and a node (17) to which a continuous input voltage to convert is applied (V1), in particular a battery voltage, a switching network including main switches (M4, M3) to selectively connect respective half-windings (13a, 13b) of said second winding (13) to a fixed voltage reference (16), in particular a ground reference, under the control of respective switching driving signals (Va, Vb), a circuit to limit (P1, P2) an in-rush current in said reactive circuit (15). According to the invention said circuit to limit (P1, P2) an in-rush current in said reactive circuit (15) includes a first circuit branch (P1) and a second circuit branch (P2), each apt to selectively place in electrical connection a respective first (13a) and second half-winding (13b) of said second winding (13) of the transformer (11) with the node (17) to which a continuous input voltage to convert is applied (V1), under the control of respective additional driving signals (Vc, Vd).