Current Mode Power Converter Transient Response Compensation
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Solution Overview
Problem
Current power converter circuits using current mode control can become unstable during certain duty cycles and suffer from increased inductor current peaks, leading to output voltage droop due to slope compensation, which affects the regulation of power supply voltages.
Innovation Solution
The power converter circuit employs an additional comparison using an uncompensated version of the sensed inductor current and a correction to the slope compensation current to extend the charge cycle, reducing errors and improving voltage regulation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If slope compensation is applied to current mode control, then stability during certain duty cycles is improved, but inductor current peak increases causing output voltage droop
Solution Approach 1:
The patent segments the current mode control into two independent comparison operations: one using uncompensated inductor current and another using slope-compensated inductor current. This segmentation allows each comparison to serve a specific function - the uncompensated version prevents excessive current peaks while the compensated version maintains stability during high duty cycles, thereby resolving the contradiction between stability and voltage regulation accuracy.
2Measurement precision
If charge cycle duration is extended to improve transient response, then voltage regulation accuracy improves, but charge cycle time increases
Solution Approach 1:
The patent applies preliminary action by performing the uncompensated current comparison in parallel with the compensated current comparison during the charge cycle. This allows the control circuit to proactively detect when the inductor current approaches the control current level and prepare to extend the charge cycle if needed, rather than waiting for voltage droop to occur. The dual-comparison mechanism enables the system to maintain accurate voltage regulation while minimizing charge cycle extension time.
Data Source
AI summary
A power converter circuit that includes a switch node coupled to a regulated power supply node via an inductor may, during a charge cycle, source current to the regulated power supply node. In response to initiating the charge cycle, a control circuit may generate a control current using a voltage level of the regulated power supply node and a reference voltage level. The control circuit may also halt the charge cycle using results from comparisons of the compensated and uncompensated versions of the inductor current to the control current.