Power Converter PWM Control for Fast Voltage Transition Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched inductor-capacitor DC-to-DC power converters experience lagging responses and over-shoot/under-shoot issues when the target output voltage changes faster than the power converter's response, leading to inefficiencies and flicker in applications like LED backlighting.
Innovation Solution
Implementing a control circuit that detects under-regulation conditions by scanning feedback voltages and increasing the clock signal rate to the counter, and using window comparators to limit the count value range for PWM control signals, thereby mitigating over-shoot/under-shoot conditions and maintaining a closed-loop response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the target output voltage changes rapidly, then the response speed of the power converter is improved, but over-shoot/under-shoot conditions occur leading to instability
Solution Approach 1:
The controller detects under-regulation conditions by scanning feedback voltages before the output voltage can fully respond to a target change. By identifying the under-regulation condition in advance and increasing the clock signal rate proactively, the system prepares for the upcoming voltage transition, allowing it to respond more quickly while maintaining stability through controlled adjustment rather than reactive correction.
2Speed
If the clock signal rate is increased to improve response speed, then the power converter responds faster to voltage changes, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the clock signal rate based on detected under-regulation conditions. During normal operation, the clock signal operates at a standard rate for energy efficiency. When an under-regulation condition is detected through feedback voltage scanning, the controller temporarily increases the clock signal rate to accelerate the power converter's response. This dynamic adjustment allows the system to achieve fast response only when necessary, minimizing overall energy consumption while maintaining the capability for rapid voltage adjustment.
3Stability of the object's composition
If window comparators are used to limit count value range, then over-shoot/under-shoot conditions are mitigated, but device complexity increases
Solution Approach 1:
The window comparators continuously monitor the relationship between the target output voltage and the actual output voltage through feedback. By comparing these voltages and detecting when their difference exceeds predefined thresholds, the system identifies under-regulation and over-regulation conditions. This feedback mechanism enables the controller to adjust the PWM control signal accordingly, mitigating over-shoot and under-shoot conditions while maintaining a relatively simple circuit architecture through efficient use of standard comparator components.
Data Source
AI summary
Circuits and methods for reducing lagging responses of a power converter to changes in circuit voltages or current, over-shoot/under-shoot when a target output voltage changes faster than the power converter's response, and open loop conditions. Embodiments include scanning a feedback voltage from a load powered by a voltage output by a power converter controlled by a PWM control signal; detecting an under-regulation condition; and, while the under-regulation condition is detected, increasing a clock signal rate to a counter outputting a count value usable to generate the PWM control signal. Embodiments include comparing a target output voltage to a signal representative of an output voltage of the power converter; indicating an under-shoot or over-shoot condition if the voltage difference exceeds a corresponding offset value; and limiting the range of values for an M-bit count value used to generate the PWM control signal to mitigate the under-shoot or over-shoot condition.