Buck-Regulated DC Bus Pre-Charging for Supercapacitor In-Rush Control
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Solution Overview
Problem
Existing DC bus systems in motor drives face inefficiencies due to transient power dissipation and incomplete energy storage during the pre-charging process, leading to high energy consumption and in-rush currents, especially when using supercapacitors for energy storage.
Innovation Solution
A DC bus system incorporating a bridge rectifier, smoothing capacitor, buck regulator, current sensor, and a supercapacitor in parallel with an electrolytic capacitor to efficiently pre-charge the DC bus, minimizing power dissipation and in-rush currents through a buck regulator control circuit that manages the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a supercapacitor is used for energy storage in a DC bus system, then energy storage capacity and current delivery capability are improved, but in-rush currents and power dissipation during pre-charging increase
Solution Approach 1:
A pre-charge circuit is introduced as an intermediary component between the power source and the supercapacitor. This circuit controls the charging process by limiting current flow during pre-charging, thereby preventing in-rush currents and reducing power dissipation while still enabling the supercapacitor to store energy effectively for later use.
Solution Approach 2:
The system performs preliminary charging of the supercapacitor through a controlled pre-charge circuit before the main operating phase. This preliminary action ensures the supercapacitor is partially charged in advance, reducing the need for high current draw during normal operation and thereby reducing overall power dissipation and in-rush current problems.
2Productivity
If a supercapacitor is directly connected to the DC bus, then energy exchange between regenerating and motoring axes is improved, but in-rush currents during initial charging increase
Solution Approach 1:
A pre-charge circuit serves as an intermediary between the power source and the supercapacitor-DC bus connection. This intermediary controls the initial charging process, allowing energy exchange between regenerating and motoring axes to proceed efficiently while preventing harmful in-rush currents during the initial charging phase.
Solution Approach 2:
The pre-charge circuit dynamically adjusts its operation based on the charging state of the supercapacitor. During initial charging, it limits current to prevent in-rush problems, but once charged, it allows full energy exchange capability between regenerating and motoring axes, thus achieving both high productivity and harm reduction.
3Object-affected harmful factors
If a pre-charge circuit is added to control supercapacitor charging, then in-rush currents are reduced, but device complexity increases
Solution Approach 1:
A relatively simple pre-charge circuit is introduced as an intermediary component to control supercapacitor charging. This circuit effectively reduces in-rush currents without requiring complex control systems, thereby achieving harm reduction with minimal increase in device complexity.
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 solution enables fast and efficient pre-charging of the DC bus with minimal power dissipation, complete energy storage, and reduced in-rush currents, allowing for peak demand support and efficient energy reuse between regenerating and motoring axes in motor drives.
Implementation Method 1
A supercapacitor is a special type of capacitor that typically stores 10 to 100 times more energy per unit volume than electrolytic capacitors
Implementation Method 2
a bridge rectifier supplied by mains supply
Implementation Method 3
a buck regulator... A control circuit for the buck regulator is provided
Data Source
AI summary
A power control system is provided for AC mains, including an input bridge rectifier connected to the AC power mains, and a buck regulator circuit connected to the DC output of the input bridge rectifier, the output of the buck regulator circuit providing a DC power output bus. A current sensor is connected to the output of the buck regulator circuit, and one or more capacitors is connected across the DC power output bus for receiving current from the buck regulator circuit. The buck regulator circuit is controlled to limit peak output current thereof.