DC-DC Converter Voltage Control for Hybrid Vehicle Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid vehicles with batteries of two different voltages, existing DC-DC converters face challenges in maintaining battery voltage above the operable lower limit during abnormal reductions, leading to potential operational failures.
Innovation Solution
A power conversion device with a control unit that calculates a manipulated variable based on detected voltage values and predetermined fixed values, preventing sharp changes and ensuring stable power supply by switching between feedback and fixed control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control and feedforward control are used to control output voltage, then voltage control precision is improved, but when input voltage is abnormally reduced, the manipulated variable calculation becomes unstable and voltage falls below the operable lower limit
Solution Approach 1:
The control method dynamically switches between different control modes based on operating conditions. When input voltage is normal, both feedback and feedforward control are used for precise voltage control. When input voltage is abnormally reduced, the system transitions to a fixed manipulated variable mode to prevent instability, thus adapting the control strategy to current conditions to maintain reliability while preserving control precision when possible
Solution Approach 2:
The system changes the control parameters based on input voltage conditions. Under normal conditions, the manipulated variable is calculated using detected voltage values for precise control. When abnormal voltage reduction is detected, the system switches to using predetermined fixed values for the manipulated variable calculation, preventing the calculation results from becoming unstable and ensuring voltage remains above the operable lower limit
2Measurement precision
If the manipulated variable is calculated using detected voltage values, then control accuracy is improved, but sharp changes in the manipulated variable occur when voltage is abnormally reduced, causing unstable power supply
Solution Approach 1:
The system takes preliminary action by detecting abnormal voltage reduction and switching to fixed manipulated variable mode before the manipulated variable can become unstable. This prevents sharp changes in the manipulated variable that would otherwise occur when detected voltage values become abnormal, thereby maintaining power supply stability while preserving control accuracy under normal conditions
Data Source
AI summary
A power conversion device including: a power conversion unit which is connected to two DC power supplies and performs power conversion; and a control unit which calculates a manipulated variable for controlling output voltage of the power conversion unit, wherein the manipulated variable for control is calculated on the basis of a voltage detection value on the primary side or the secondary side of the power conversion unit and a predetermined fixed value.