Switched-Mode Power Supply OFF-Skip Control for Stable Load Response
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Solution Overview
Problem
Existing switched-mode power supplies face challenges in OFF-skip control, particularly when the difference between input and output voltages is small, leading to suboptimal output voltage regulation and potential drops in load response characteristics.
Innovation Solution
The power-supply control apparatus incorporates an OFF-skip function that skips cyclic OFF transitions of the output device, extending the switching cycle and ON duty by dividing the switching frequency, and employs a pseudo-current generating circuit to stabilize feedback control loops, ensuring the output device remains ON even when the reset signal is low, thereby maintaining load response characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If OFF-skip control is implemented to extend switching cycle and improve response characteristics, then load response characteristics are improved, but output voltage regulation may deteriorate due to skipping cyclic OFF transitions
Solution Approach 1:
The patent implements dynamic switching between two control modes: normal PWM control and OFF-skip control. The controller dynamically selects the appropriate mode based on operating conditions, allowing the system to adapt between maintaining strict voltage regulation and improving load response characteristics as needed
Solution Approach 2:
The patent changes the control parameter by introducing a flag signal that modifies the switching behavior. When the flag is set, the controller skips cyclic OFF transitions and extends the switching cycle, effectively changing the duty cycle behavior to improve response while maintaining voltage regulation through the flag-controlled logic
2Speed
If the switching frequency is divided to extend the switching cycle, then power-supply response is improved, but the complexity of control logic increases
Solution Approach 1:
The patent segments the control logic into distinct functional blocks: a flag setting unit that determines when OFF-skip control should be activated, a comparator that generates the reset signal, and a controller that executes the switching based on these inputs. This modular segmentation makes the complex control logic more manageable and implementable
Data Source
AI summary
A power-supply control apparatus includes a controller that is configured to perform duty control on a switch device which forms an output stage of a switched-mode power supply which is configured to generate an output voltage from an input voltage. The controller has an OFF-skip function to skip cyclic OFF transitions of the switch device. The controller keeps the switch device turned ON by ignoring a reset signal based on feedback control on the output voltage under a state in which the OFF-skip function is implemented.