DC/DC Converter Dynamic Inductor Current Limiting
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Solution Overview
Problem
Existing DC/DC converters with feed forward control systems face challenges in maintaining power conversion efficiency, particularly under varying load conditions, as they often experience reduced efficiency due to ripple voltage and inefficiencies in inductor current management.
Innovation Solution
A DC/DC converter is designed with an inductor current detector, load current detector, and control circuit that dynamically adjusts the upper limit value of the inductor current based on load current and input voltage, ensuring the inductor current does not exceed this limit, thereby optimizing the on and off times of the switching element to enhance power conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the upper limit value of inductor current is increased to improve power conversion efficiency, then power conversion efficiency is improved, but ripple voltage increases and stability deteriorates
Solution Approach 1:
The patent applies dynamics by making the upper limit value of inductor current variable rather than fixed. The control circuit dynamically adjusts the upper limit value based on the switching period, increasing it when the switching period is long and decreasing it when the switching period is short. This dynamic adjustment allows the system to maintain high power conversion efficiency across different operating conditions while preventing excessive ripple voltage that would occur with a constantly high current limit.
Solution Approach 2:
The patent changes the parameter of inductor current upper limit value based on the switching period. By establishing a relationship where the upper limit value varies with the switching period (higher limit for longer periods, lower limit for shorter periods), the system optimizes power conversion efficiency while maintaining output stability. This parameter change approach resolves the contradiction by adapting the current limit to actual operating conditions rather than using a fixed value.
2Stability of the object's composition
If the upper limit value of inductor current is decreased to reduce ripple voltage, then output voltage stability is improved, but power conversion efficiency deteriorates
Solution Approach 1:
The system uses dynamic adjustment of the inductor current upper limit value based on switching period. When the switching period is short, the upper limit value is set lower to reduce ripple voltage and maintain stability. When the switching period is long, the upper limit value is increased to improve power conversion efficiency. This dynamic behavior resolves the contradiction by adapting the current limit to the actual operating conditions rather than using a fixed conservative value.
Solution Approach 2:
The patent implements parameter changes by making the inductor current upper limit value a function of the switching period. The control circuit adjusts this parameter in real-time based on detected switching period variations, allowing the system to achieve both stability (when period is short) and efficiency (when period is long), thereby resolving the contradiction between these two opposing requirements.
3Measurement precision
If feedback control is used to accurately set output voltage, then output voltage accuracy is improved, but oscillation risk increases and control complexity increases
Solution Approach 1:
The patent incorporates feedback control mechanisms to accurately determine the switching period based on actual operating conditions. The control circuit uses feedback information about the switching period to dynamically adjust the upper limit value of inductor current. This feedback approach enables accurate output voltage control while using the period information to prevent oscillations by appropriately setting current limits, thus resolving the contradiction between accuracy and reliability.
4Speed
If the switching element operates at high frequency to improve response speed, then response speed is improved, but power conversion efficiency deteriorates due to increased switching losses
Solution Approach 1:
The patent applies dynamics by adjusting the upper limit value of inductor current based on the detected switching period. When switching frequency is high (short period), the upper limit value is set lower to reduce switching losses and improve efficiency. When switching frequency is low (long period), the upper limit value is increased to maintain efficiency. This dynamic adjustment resolves the contradiction between response speed and power conversion efficiency.
Solution Approach 2:
The control circuit changes the parameter of inductor current upper limit value according to the switching period detected through feedback. This parameter adaptation allows the system to operate efficiently at different switching frequencies by optimizing the current limit for each operating condition, thereby resolving the contradiction between fast response (high frequency) and power conversion efficiency.
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
This configuration improves power conversion efficiency by ensuring the inductor current is managed within optimal limits, leading to more stable and efficient operation across different load conditions.
Implementation Method 1
Energy is stored in an inductor while the switching element is in the on state
Implementation Method 2
When the current flowing through the inductor exceeds an upper limit value with time, the switching element is brought to an off state
Data Source
AI summary
In a DC/DC converter, a control circuit determines an upper limit value of an inductor current based on a load current and an input dc voltage, and changes at least one of an on time and an off time of a switching element in such a manner that the detected inductor current does not exceed the upper limit value.