Power Conversion Device Dynamic DC Bus Voltage Control
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Solution Overview
Problem
Existing power conversion devices lack the ability to appropriately adapt to various types of storage batteries with different ratings and characteristics, particularly during charging and discharging processes, which can lead to damage due to sharp changes in charge current and voltage, especially in lithium-ion batteries used in electric automobiles and home storage systems.
Innovation Solution
A power conversion device with a DC/DC conversion circuit and a DC/AC conversion circuit, controlled by a control circuit that selects between step-up and step-down control methods based on storage battery voltage, state of charge, and DC bus voltage, to set a control target value for the DC bus voltage, ensuring appropriate processing control for different types of storage batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed control range of DC bus voltage is set based on AC system voltage, then the power conversion device can operate with the AC system, but it cannot adapt to various types of storage batteries with different voltage ratings and characteristics
Solution Approach 1:
The patent implements dynamic control range adjustment by making the DC bus voltage control range variable based on storage battery characteristics. The control range is no longer fixed but adapts dynamically to match different battery voltage ratings and operational requirements, enabling the system to handle various battery types without hardware changes
Solution Approach 2:
The patent changes the control parameters of the DC bus voltage based on detected storage battery characteristics. By adjusting voltage thresholds and control targets according to battery type, the system achieves adaptability to different battery ratings while maintaining a unified control architecture
2Productivity
If charge current is sharply changed during storage battery charging, then charging speed increases, but metal lithium precipitates and the storage battery may be damaged
Solution Approach 1:
The patent implements periodic or staged charge current adjustment based on storage battery state. Rather than applying maximum current continuously, the system periodically evaluates battery status and adjusts current in stages, preventing sharp changes that cause lithium precipitation while maintaining efficient charging progression
Solution Approach 2:
The patent uses feedback control by continuously monitoring storage battery state and adjusting charge current accordingly. The control system receives feedback on battery conditions and dynamically modulates charging current to stay within safe operational limits, preventing damage while optimizing charging speed
3Adaptability or versatility
If various types of storage batteries with different ratings are processed, then system versatility improves, but control precision for individual battery characteristics deteriorates
Solution Approach 1:
The patent performs preliminary detection and classification of storage battery characteristics before charging begins. By identifying battery type, voltage rating, and specific parameters in advance, the system pre-configures appropriate control parameters, ensuring both versatility across battery types and precision for each individual battery's specific requirements
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 efficient and safe charging and discharging of various storage batteries by adapting to their specific ratings and characteristics, minimizing damage and optimizing power conversion, thereby extending battery life and ensuring reliable operation.
Implementation Method 1
a DC/DC conversion circuit for performing conversion between storage battery voltage of the storage battery and DC bus voltage
Implementation Method 2
a DC/AC conversion circuit for performing conversion between the DC bus voltage and AC voltage of the AC system
Implementation Method 3
a lithium-ion battery used as a storage battery in an electric automobile or a home storage battery system is charged or discharges power by chemical reaction
Data Source
AI summary
A power conversion device connected between a storage battery and AC system charges the storage battery with power from the AC system and discharges power from the storage battery to the AC system. The power conversion device includes a DC/DC conversion circuit performing conversion between a storage battery voltage and DC bus voltage, a DC/AC conversion circuit performing conversion between the DC bus voltage and AC voltage of the AC system, and control circuits controlling the DC/DC and DC/AC conversion circuits. The control circuits select either step-up control or step-down control for the DC/DC conversion circuit based on the storage battery voltage, the storage battery charge state, and a control range of the DC bus voltage, set a control target value of the DC bus voltage, and control the DC/DC and DC/AC conversion circuits by the selected control method so the DC bus voltage becomes the control target value.