Switching Power Supply Current Mode Control Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switching power supply circuits face challenges with low processing speed and poor response, particularly in high-frequency applications, due to low resistance values causing voltage drops and increased offset voltage instability.
Innovation Solution
A switching power supply circuit with a feedback control system that includes current mode control and current correction signal generation, utilizing MOS transistors and resistances to generate current mode and correction signals, which are then used to adjust the duty ratio and ON-period of switching signals for improved control and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the resistance values of the switching means and current detection resistance are lowered to improve conversion efficiency, then energy loss is reduced, but the voltage drop at the current detection resistance decreases causing offset voltage instability
Solution Approach 1:
The patent introduces a current detection resistance with a relatively high resistance value as an intermediary element to detect the switching current. This high-value detection resistance generates a sufficient voltage drop for accurate current detection, while the offset voltage compensation circuit acts as a mediator to eliminate the destabilizing effect of the offset voltage, thus resolving the contradiction between energy efficiency and circuit stability.
Solution Approach 2:
The patent changes the resistance value parameter of the current detection resistance to be relatively high, which enables sufficient voltage drop for current detection. Additionally, the offset voltage compensation circuit dynamically adjusts parameters to compensate for offset voltage variations, thereby maintaining circuit stability despite the high detection resistance value.
2Measurement precision
If a differential amplifier is used to amplify the current signal, then measurement precision is improved, but the processing speed decreases and response becomes poor
Solution Approach 1:
The patent replaces the conventional differential amplifier-based current feedback system with a current mode control system that uses current-mode signal processing. This substitution eliminates the need for high-gain differential amplifiers and their associated feedback loops, thereby achieving both high measurement precision and fast processing speed suitable for high-frequency switching applications.
Solution Approach 2:
The patent introduces a current information signal as an intermediary that directly represents the switching current without requiring amplification. This current information signal is generated by the high-value current detection resistance and is processed in current mode, enabling fast response while maintaining detection precision.
3Productivity
If the switching frequency is increased to improve productivity, then output per unit time is improved, but the response quality deteriorates due to poor current feedback response
Solution Approach 1:
The patent replaces the voltage-mode feedback system with a current mode control system that processes current signals directly. This substitution enables the system to maintain stable control even at high switching frequencies, as the current mode processing provides faster response and better bandwidth, thus improving productivity without sacrificing control stability.
Solution Approach 2:
The patent employs periodic switching action at high frequencies with the current mode control system maintaining stability through its inherent fast response characteristics. The current information signal is continuously updated at each switching cycle, enabling the system to adapt quickly to changes and maintain stable operation at high productivity levels.
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 enables a swift and stable response to circuit currents, enhancing the stability and performance of the switching power supply circuit, particularly in high-frequency applications.
Implementation Method 1
a current ISW flowing into the switching means SW1 is formed into a current information signal S21 by utilization of a voltage at a point of connection between the switching means SW1 and a current detection resistance Rsen
Implementation Method 2
current mode signal generation means for generating a current mode signal being a drain current or a source current of a first MOS transistor obtained by supplying a first current information signal, which is an output signal of the current detection means, to a gate of the first MOS transistor
Data Source
AI summary
A switching power supply circuit has a current mode control circuit including current detection means, and current mode signal generation means for generating a current mode signal being a drain current of a first MOS transistor obtained by supplying a first current information signal, which is an output signal of the current detection means, to the gate of the first MOS transistor, and by connecting a first resistance to the source of the first MOS transistor, and supplies the current mode signal to a feedback control system of the switching power supply circuit.