Power Converter Rush Current Control via Limiting Resistor
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Solution Overview
Problem
Existing power converters experience excessive rush currents during the initial charging of capacitors when connecting distributed power sources or power storage systems, leading to potential damage due to voltage differences, and existing solutions increase complexity with additional components like switches and resistors.
Innovation Solution
A power converter with a harmonic filter in the AC circuit and a DC capacitor, using a limiting resistor to control the current applied to the DC capacitor, and monitoring the voltage difference to safely connect the power storage device by switching on the DC breaker based on the monitored difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch and electromagnetic switch with resistor are added to limit rush current, then the rush current can be controlled, but the device complexity increases
Solution Approach 1:
The patent introduces a limiting resistor as an intermediary component between the power source and the capacitor. This resistor temporarily limits the rush current during capacitor charging without requiring complex switching mechanisms. The resistor serves as a simple mediator that protects the system during the critical initial charging phase.
Solution Approach 2:
The patent applies preliminary action by pre-charging the capacitor through the limiting resistor before the main power connection is established. This preliminary charging process occurs through a separate charging circuit that uses the resistor to safely initialize the capacitor voltage, preventing rush current before the main system operates.
2Speed
If the capacitor is charged directly from the power source, then the charging process is fast, but excessive rush current damages the devices
Solution Approach 1:
The limiting resistor acts as an intermediary that enables safe charging by being placed in series with the capacitor during the initial charging phase. It mediates between the power source and capacitor, allowing charge flow while limiting current to safe levels, thus preventing damage during the charging process.
Solution Approach 2:
The charging process is segmented into two distinct phases: an initial charging phase through the limiting resistor, and a subsequent normal operation phase. This segmentation allows the system to handle the dangerous initial charging separately from the normal operating conditions, protecting the system during the critical transition phase.
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
Prevents excessive rush currents during the start process by controlling the current to the DC capacitor, simplifying the configuration and reducing the risk of damage while ensuring safe connection to the power storage device.
Implementation Method 1
a current limited by a limiting resistor is given from the electric power system side to the DC capacitor
Implementation Method 2
performs AC/DC conversion using an inverter
Implementation Method 3
the power converter is connected to the power storage device by switching on the DC breaker on the basis of the monitored difference
Data Source
AI summary
A power converter with a simple configuration capable of controlling a rush current is provided. The power converter is installed between an electric power system and a power storage device, includes a harmonic filter in an AC circuit on the electric power system side and a DC capacitor and a DC breaker in a DC circuit on the power storage device side, and performs AC/DC conversion processing using an inverter. The power converter is configured in such a way that, when the power storage device starts running, a current limited by a limiting resistor is given from the electric power system side to the DC capacitor, the difference between the voltage of the DC capacitor and the voltage of the power storage device is monitored, and the power converter is connected to the power storage device by switching on the DC breaker on the basis of the difference.