Adaptive Pulse-Skipping Control in Switching Converters
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Solution Overview
Problem
Existing switching converters with pulse skipping mode are limited in application scope due to fixed clamping voltage levels, making them unsuitable for varying input and output voltages, leading to incorrect judgment in pulse skipping mode entry.
Innovation Solution
Adaptive adjustment of the judgment criterion for pulse skipping mode based on input and output voltage variations, using a feedback control circuit to generate a pulse skipping reference signal related to the duty ratio of the PWM signal, and incorporating a ramp signal indicative of inductor current changes to optimize pulse skipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-level clamping voltage is used for pulse skipping mode judgment, then the switching converter can operate in pulse skipping mode, but the application scope is limited to fixed input and output voltage levels
Solution Approach 1:
The patent transforms the fixed clamping voltage into a dynamic pulse skipping reference signal that adapts to varying input and output voltages. The pulse skipping circuit generates this reference signal by comparing the error amplification signal with a ramp signal, creating a duty ratio signal that dynamically adjusts the pulse skipping threshold based on actual operating conditions, thereby resolving the contradiction between adaptability and judgment accuracy.
Solution Approach 2:
The invention changes the parameter of the reference voltage from a fixed level to a dynamically adjustable pulse skipping reference signal. This signal's threshold varies according to the duty ratio of the PWM signal and the ramp signal comparison, allowing the pulse skipping mode judgment to remain accurate across different input and output voltage conditions while expanding application scope.
2Loss of energy
If pulse skipping mode is entered during light-load condition, then switching loss is reduced, but incorrect judgment occurs when input or output voltage varies
Solution Approach 1:
The patent implements a feedback mechanism where the pulse skipping reference signal is generated based on the error amplification signal and ramp signal comparison. This feedback loop continuously monitors the actual operating conditions and adjusts the pulse skipping threshold accordingly, ensuring that pulse skipping mode is correctly judged and entered only under appropriate light-load conditions, even when input or output voltages vary.
Solution Approach 2:
By making the pulse skipping reference signal dynamic rather than fixed, the system can accurately determine pulse skipping mode entry conditions across varying voltage levels. The duty ratio signal dynamically adjusts the reference threshold to match current operating conditions, preventing incorrect judgment while maintaining energy efficiency during genuine light-load periods.
3Adaptability or versatility
If a fixed clamping voltage level is used, then the circuit design is simple, but the switching converter can only be applicable for fixed voltage levels
Solution Approach 1:
The pulse skipping circuit serves multiple functions: it generates the pulse skipping reference signal, compares it with the error amplification signal, and dynamically adjusts the pulse skipping threshold based on the duty ratio signal. This multi-functional approach allows the converter to operate across a wide voltage range without requiring separate circuits for different voltage conditions, achieving universality while managing complexity through functional integration.
Data Source
AI summary
A switching converter having pulse skipping mode includes a power stage circuit, a feedback control circuit, an operating signal generator circuit and a pulse skipping circuit. The feedback control circuit generates an initial pulse width modulation (PWM) signal according the output power. The operating signal generator circuit masks a part of pulses of a clock signal according to a pulse width of a pulse skipping signal, so as to generate an adjusted PWM signal. The pulse skipping circuit adaptively generates a duty ratio signal according to an input voltage and an output voltage, so as to generate the pulse skipping reference signal related to a duty ratio of the initial PWM signal. The pulse skipping circuit compares an amplification signal with the pulse skipping reference signal to generate the pulse skipping signal. The power stage circuit converts the input power to the output power according to the adjusted PWM signal.