DC-DC Converter Current Limiting Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DC-DC converter circuits face challenges in maintaining constant current limitation independent of the on/off times of the switching signal, leading to subharmonic oscillations and inefficient energy transfer, especially at higher duty cycles.
Innovation Solution
A circuit for DC-DC conversion with current limitation that includes a current limiter and a slope compensation circuit, which generates a control signal based on the sum of a periodic signal and a measurement signal dependent on the coil current, and a correction circuit to reduce dependence on the duty cycle, ensuring stable current limitation and preventing subharmonic oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If slope compensation circuit is used to stabilize the controller and prevent subharmonic oscillations, then the stability of the controller is improved, but the current limitation level becomes dependent on the duty cycle of the switching signal
Solution Approach 1:
The patent implements a feedback mechanism where the current limitation threshold is dynamically adjusted based on the duty cycle of the switching signal. The control circuit monitors the duty cycle and modifies the current limitation threshold accordingly, ensuring that the actual current limitation remains constant despite changes in switching parameters. This feedback approach resolves the contradiction by allowing the system to maintain both stability through slope compensation and duty cycle independence through adaptive threshold adjustment.
2Use of energy by moving object
If the on/off time ratio of the controllable switch is increased to provide more energy to the load, then the energy delivery to the load is improved, but the peak current through the coil is limited to smaller values due to slope compensation
Solution Approach 1:
The patent changes the parameter being controlled from fixed peak current limitation to fixed energy delivery. By making the current limitation threshold dependent on the duty cycle, the system ensures that the product of current and time (energy) remains constant rather than the current alone. This allows the system to deliver consistent energy to the load regardless of the switching frequency or duty cycle, resolving the contradiction between energy delivery and peak current limitation.
Data Source
AI summary
A circuit for DC-DC conversion with current limitation comprises a DC-DC converter (100) with a coil (110) and a controllable switch (120) that can be switched into a low-impedance and a high-impedance state, and a current limiter (300a, 300b) for generating a control signal (IOC) for controlling the state of the controllable switch in the DC-DC converter (100). The current limiter (300a, 300b) is constructed such that the current (IL) through the coil at which the current limitation takes place is nearly independent of the ratio of the on-times and off-times of the controllable switch in the DC-DC converter (100).