Switch Power Supply Controller Dynamic Off-Time Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switch mode power supplies face challenges in maintaining efficient operation during load changes, particularly in preventing inductance current overshoot and ensuring stable start-up when the load transitions from a short-circuit to a heavy load, as existing methods often resort to frequency reduction, which can lead to discontinuous conductive mode and slow start issues.
Innovation Solution
A switch power supply controller that includes a switch time regulating circuit to compare the duration of the first state against an expected duration, adjusting the second state duration in real-time to maintain a constant on or off time, thereby preventing inductance current overshoot and ensuring continuous conductive mode operation by intelligently adjusting the operating frequency based on actual switch cycle conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency reduction is used to prevent inductance current overshoot during load transitions, then current overshoot is reduced, but the power supply enters discontinuous conductive mode and start-up becomes slow
Solution Approach 1:
The patent implements dynamic adjustment of the switch off-time based on real-time detection of inductance current status. The controller dynamically extends the off-time when current overshoot is detected and reduces it when current is below threshold, enabling adaptive response to load changes without fixed frequency reduction. This dynamic control maintains continuous conductive mode while preventing overshoot.
Solution Approach 2:
The patent employs feedback control by continuously monitoring the inductance current through detection circuits and comparing it against threshold values. The controller uses this feedback information to adjust the switch off-time in real-time, creating a closed-loop control system that prevents current overshoot while maintaining stable operation and fast start-up response.
2Stability of the object's composition
If frequency reduction is applied during load transitions, then inductance current stability is improved, but operating frequency becomes uncontrolled and conductive mode becomes discontinuous
Solution Approach 1:
The patent maintains dynamic control of the switch off-time rather than reducing frequency. The off-time is adjusted in real-time based on inductance current detection, allowing the controller to extend off-time temporarily for stability during transitions while maintaining overall frequency control. This prevents discontinuous conductive mode by keeping the switch active long enough to maintain current flow.
Solution Approach 2:
The patent changes the timing parameter (off-time duration) rather than the frequency parameter. By extending or reducing off-time based on current thresholds, the controller achieves current stability through parameter adjustment without affecting the fundamental operating frequency, thereby maintaining continuous conductive mode operation.
3Device complexity
If conventional control methods are used during short-circuit to heavy load transition, then simplicity is maintained, but inductance current overshoot occurs and start-up fails
Solution Approach 1:
The patent introduces an intermediary detection circuit that monitors inductance current and provides intermediate control signals to the switch controller. This intermediary layer translates current status into appropriate off-time adjustments, enabling reliable start-up during difficult transitions without requiring complex overall system redesign. The intermediary circuit acts as a buffer between simple detection and control actions.
Solution Approach 2:
The patent performs preliminary detection of inductance current status before making control decisions. By detecting current thresholds in advance and preparing appropriate off-time adjustments, the controller prevents overshoot and ensures successful start-up before the actual load transition occurs, rather than reacting after problems arise.
Data Source
AI summary
In one embodiment, a switch power supply controller can include: (i) a switch configured to operate in first and second states during each switch cycle; (ii) a switch time regulating circuit that compares a duration of the first state in a present switch cycle against an expected first state duration; (iii) the switch time regulating circuit decreasing a duration of the second state in the present switch cycle when the first state duration is greater than the expected first state duration, to decrease a first state duration for a next switch cycle; and (iv) the switch time regulating circuit being increasing the second state duration in the present switch cycle when the first state duration is less than the expected first state duration, to increase a first state duration for a next switch cycle.