DC Bus Capacitor Charging Without a Loop to Limit Inrush Current
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Solution Overview
Problem
The rapid switching of different energy sources into a direct-current (DC) bus generates a large impact current, causing damage to bus capacitors and components, and poses safety hazards such as fire and explosion.
Innovation Solution
A power supply circuit without a charging loop, utilizing an alternating current switch component and a photovoltaic switching component to control the voltage rise across the DC bus capacitor to a target voltage, using insulated gate bipolar transistors (IGBTs) and pulse width modulation signals to alternately turn on switches, preventing rapid voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large capacity direct-current bus capacitor is configured to maintain voltage stability, then voltage stability is improved, but impact current increases causing damage to components and safety hazards
Solution Approach 1:
The patent introduces a current limiting reactor as an intermediary component between the energy source and the direct-current bus capacitor. This reactor limits the rate of current change (di/dt) during switching transitions, thereby preventing large impact currents from reaching the capacitor while still allowing the capacitor to maintain voltage stability. The reactor acts as a buffer that mediates between the switching action and the capacitor charging process.
Solution Approach 2:
The patent implements preliminary control actions through switching components that regulate the charging process before full power is applied to the bus capacitor. By controlling the switching timing and sequence, the system prepares the capacitor charging process in advance, gradually building up voltage and current levels to avoid sudden impact currents while ensuring voltage stability is maintained throughout the process.
2Object-affected harmful factors
If switching components are used to control energy source connection, then impact current is reduced, but device complexity increases
Solution Approach 1:
The patent segments the switching control into multiple independent switching components, each responsible for specific phases or functions of the energy source connection. This segmentation allows each switch to be controlled independently with simpler control logic, while collectively they achieve the complex function of impact current reduction. The segmentation also facilitates modular design and easier maintenance.
3Object-affected harmful factors
If conventional current limiting methods are used, then impact current is controlled, but energy loss increases and safety concerns remain
Solution Approach 1:
The patent replaces conventional passive current limiting methods (which rely on resistive elements causing energy loss) with an active switching control system. Instead of using resistors to limit current (which dissipate energy as heat), the system uses electronically controlled switching components that regulate current flow with minimal energy loss. This substitution maintains impact current control while significantly reducing energy waste.
Data Source
AI summary
The present disclosure provides a power supply circuit without a charging loop, and a power management system. The power supply circuit comprises an alternating current switch component, a photovoltaic switching component and a direct-current bus capacitor. The alternating current switch component is configured to electrically connect a live wire of a three-phase alternating current to a direct-current bus, and cause, when an alternating current is selected to charge the direct-current bus capacitor, a voltage across two ends of a direct-current bus capacitor to steadily rise to a target voltage. The photovoltaic switching component is configured to electrically connect a photovoltaic power supply to the direct-current bus, and cause, when the photovoltaic power supply is selected to charge the direct-current bus capacitor, the voltage across the two ends of the direct-current bus capacitor to steadily rise to the target voltage. The direct-current bus capacitor is electrically connected between a positive electrode and a negative electrode of the direct-current bus. When the alternating current or the photovoltaic power supply is electrically connected to the direct-current bus, the alternating current switch component or the photovoltaic switching component can control the voltage across the two ends of the direct-current bus capacitor to stably rise to the target voltage, thereby preventing causing damage to components on the direct-current bus by a large impact current generated by a rapid rise of the voltage across the two ends of the direct-current capacitor.