DC-DC Converter Control with Duty Gradient Limiting
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Solution Overview
Problem
DC-DC converters experience severe electrical current changes, particularly in boost mode, which can lead to component overload and potential damage due to rapid current rises or falls, existing control methods failing to adequately prevent these hazardous states.
Innovation Solution
Implementing a closed-loop control system with a third control device that limits the gradient of the controlled variable, such as the duty factor for switching elements, using input and output voltage values to setpoint voltage or current limits, thereby preventing excessive current changes and maintaining component safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the controlled variable is adjusted quickly to achieve rapid voltage or current changes, then the response speed is improved, but the current gradient becomes excessively steep causing component overload and potential damage
Solution Approach 1:
The control system performs preliminary action by predicting the future current gradient based on the present current and the change in controlled variable, and preemptively limits the controlled variable adjustment before excessive current changes occur. This prevents component overload while maintaining rapid response capability.
Solution Approach 2:
The system dynamically adjusts the controlled variable with time-varying constraints. The maximum allowable change in controlled variable is adapted based on operating conditions (input voltage, output voltage, present current), allowing faster response when safe and preventing overload when risks exist.
2Reliability
If the gradient of the controlled variable is limited to prevent excessive current changes, then component safety is improved, but the response speed decreases
Solution Approach 1:
The system employs dynamic gradient limiting where the maximum allowable change in controlled variable (dR_max) is continuously adapted based on operating conditions. When the converter operates in safe regions, larger adjustments are permitted for faster response. When approaching hazardous states, the gradient limit is reduced to prevent overload, thus maintaining component safety while optimizing response speed throughout the operating range.
Solution Approach 2:
The control system changes the parameter dR_max (maximum allowable controlled variable change) dynamically based on operating conditions including input voltage, output voltage, and present current. This parameter adaptation allows the system to maintain component safety through gradient limiting while preserving rapid response capability when operating conditions permit.
Data Source
AI summary
The present invention relates to the control of a DC-DC converter, wherein the gradient of a controlled variable is limited for the control of the DC-DC converter. A maximum current change in the DC-DC converter can be limited by limiting the gradient of the controlled variable in order to optionally prevent dangerous operating states of the DC-DC converter.