Frequency Converter DC Bus Parallel Control Logic
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Solution Overview
Problem
In frequency converter systems with a common DC bus scheme, low-power frequency converters experience overloading and overheating due to sharing current demands with high-power converters, leading to potential damage and inefficiency in energy management.
Innovation Solution
Implementing intelligent control logic to dynamically turn on or off the bus parallel connection between frequency converters, using existing circuit adjustments and operating mode controls, which includes IGBTs and diodes in braking units to manage bus voltage sharing and prevent rectifier bridge overload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If frequency converters of different powers include buses connected in parallel to share surplus energy, then energy wastage is reduced, but the rectifier bridge of the low-power frequency converter is easily damaged due to overloading
Solution Approach 1:
The patent implements dynamic control of the DC bus parallel connection through control logic that monitors bus voltage and selectively connects or disconnects frequency converters based on real-time operating conditions. This dynamic approach allows the system to share energy when safe while preventing overload conditions, resolving the contradiction between energy efficiency and reliability.
Solution Approach 2:
The control logic continuously monitors bus voltage and operating states of frequency converters, using this feedback information to make intelligent decisions about connecting or disconnecting converters from the parallel DC bus configuration. This feedback mechanism prevents low-power converters from being overloaded while maintaining energy sharing benefits.
2Productivity
If a low-power frequency converter shares a common DC bus with a high-power frequency converter, then energy can be shared, but the rectifier bridge of the low-power converter becomes overloaded and overheats
Solution Approach 1:
The control logic acts as an intermediary that manages the connection between frequency converters and the common DC bus. It monitors current flow and bus voltage, inserting control actions to prevent excessive current from damaging the low-power converter's rectifier bridge while still enabling energy sharing when conditions are safe.
3Loss of energy
If the bus parallel connection is always on for energy sharing, then energy efficiency improves, but the low-power frequency converter cannot handle high current demands
Solution Approach 1:
The system dynamically adjusts the DC bus parallel connection based on real-time monitoring of bus voltage and converter operating states. The control logic connects converters when energy sharing is beneficial and safe, and disconnects when current demands exceed the low-power converter's handling capacity, optimizing both energy efficiency and system safety.
Data Source
AI summary
A frequency converter adapted to be connected to another frequency converter via a direct current bus is provided. The frequency converter comprises: a positive bus interface adapted to be interconnected with a positive bus interface of the other frequency converter; an external bleeder resistor interface adapted to be interconnected with an external bleeder resistor interface of the other frequency converter; and a first control logic which controls a parallel connection, between the frequency converter and the other frequency converter and realized by a direct current bus, to be turned on or off. A corresponding frequency converter assembly, a control method, and a computer readable storage medium are also provided.