Power Converter Startup Circuit Pre-Charging
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Solution Overview
Problem
Conventional resonant power conversion circuits with expandable duty-cycle topology face challenges in controlling the startup process and pre-charging of flying and output capacitors, leading to high current inrush that can damage electronic components, necessitating the use of costly high-current-resistant components.
Innovation Solution
A power conversion system that includes a start-up circuit to pre-charge the flying and output capacitors to a preset voltage during startup, using a magnetic element with electromagnetically coupled windings and an inductor to generate a resonant current, allowing for the use of cost-effective electronic components by avoiding high current impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power conversion circuit is started up without pre-charging, then the startup process is simple, but large current is generated that can damage electronic components
Solution Approach 1:
The patent applies preliminary action by pre-charging the flying capacitor and output capacitor to preset voltages before the main power conversion circuit starts operating. The start-up circuit generates an alternating voltage that charges these capacitors in advance, ensuring that when the main circuit switches on, no large inrush current is generated, thus protecting electronic components from damage.
2Reliability
If high current-resistant electronic components are used, then component damage risk is reduced, but system cost increases
Solution Approach 1:
By pre-charging capacitors before the main circuit operates, the patent eliminates the need for expensive high current-resistant components. The start-up circuit prepares the capacitors in advance, allowing standard, cost-effective components to be used in the main power conversion circuit while still protecting against current damage.
3Object-affected harmful factors
If the start-up circuit pre-charges capacitors, then current inrush is reduced, but the start-up circuit complexity increases
Solution Approach 1:
The patent introduces a start-up circuit as an intermediary system that generates alternating voltage through electromagnetically coupled windings to pre-charge the capacitors. This intermediary circuit acts as a buffer between the power source and the main power conversion circuit, eliminating harmful current inrush while using relatively simple electromagnetic coupling components.
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
The system effectively reduces the risk of component damage from high current inrush and enables the use of cost-effective components by ensuring capacitors are pre-charged before the startup process, thereby enhancing the reliability and economic viability of the power conversion system.
Implementation Method 1
The magnetic element includes two first windings. The two first windings are electromagnetically coupled with each other. A first one of the two first windings is electrically connected between a first one of the two switch groups and the second terminal of the power conversion circuit.
Implementation Method 2
The resonant power conversion circuit having a non-isolated circuit topology with an expandable duty-cycle is widely used in the high current application.
Data Source
AI summary
A power conversion system includes a power conversion circuit and a start-up circuit. The power conversion circuit includes an output capacitor, a first switching unit, a second switching unit, a flying capacitor and a magnetic element. The second switching unit includes two switch groups. The flying capacitor is connected between a first terminal and a second terminal of the power conversion circuit. The magnetic element includes two first windings that are electromagnetically coupled with each other. A first one of the two first windings is electrically connected between one switch group and the second terminal of the power conversion circuit. A second one of the two first windings is electrically connected between the other switch group and the second terminal of the power conversion circuit. The start-up circuit includes a third winding and an inductor. The third winding is electromagnetically coupled with the first windings.