On-Time Power Converter Control for Stable Switching Frequency

Solution Overview

Problem

Conventional power converters experience increased switching frequency and decreased off periods due to variations in load, necessitating improvements in frequency adjustment.

Innovation Solution

An on-time controller and frequency adjusting circuit that senses the output voltage and generates a load sensing current to compensate the reference voltage, adjusting the on-time signal and switching frequency of the switch circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the loading of the power converter is increased, then the output voltage is maintained, but the off period decreases and the switching frequency increases

Engineering Contradiction:

Improveoutput voltage maintenanceVSAvoidoff period

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements a feedback mechanism where the off period is sensed and fed back to the on-time controller. The on-time controller adjusts the on-time signal duration based on this feedback to maintain a substantially constant switching frequency despite load variations. This closed-loop control ensures that as load increases and off period decreases, the on-time is extended proportionally to compensate.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the on-time parameter (duration of on-time signal) in response to load variations. By adjusting the on-time signal duration based on sensed off period changes, the system maintains constant switching frequency. This parameter adaptation allows the converter to operate reliably across different load conditions without fixed timing constraints.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the loading of the power converter is increased, then the output voltage is maintained, but the switching frequency increases

Engineering Contradiction:

Improveoutput voltage maintenanceVSAvoidswitching frequency

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent implements a feedback mechanism where the off period is sensed and fed back to the on-time controller. The on-time controller adjusts the on-time signal duration based on this feedback to maintain a substantially constant switching frequency despite load variations. This closed-loop control ensures that as load increases and off period decreases, the on-time is extended proportionally to compensate.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the on-time parameter (duration of on-time signal) in response to load variations. By adjusting the on-time signal duration based on sensed off period changes, the system maintains constant switching frequency. This parameter adaptation allows the converter to operate reliably across different load conditions without fixed timing constraints.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a conventional constant on-time generator is used, then the switching operation is simple, but the switching frequency varies with load changes

Engineering Contradiction:

Improveswitching operation simplicityVSAvoidswitching frequency stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the off period is sensed and fed back to the on-time controller. The on-time controller adjusts the on-time signal duration based on this feedback to maintain a substantially constant switching frequency despite load variations. This closed-loop control ensures that as load increases and off period decreases, the on-time is extended proportionally to compensate.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent transitions from a static constant on-time generator to a dynamic on-time controller that adapts its output based on real-time load conditions. The controller dynamically adjusts the on-time signal duration in response to sensed off period variations, enabling the system to maintain stable switching frequency while accommodating changing operational requirements.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12531469B2On-time controller, power converter and switching operation method for the power converter

Publication Date: 2026.01.20 CYNTEC

AI summary

An on-time controller, for controlling a switching operation of a power converter includes an on-time controlling circuit, configured to control an on-time signal of a switch circuit of the power converter according to a reference voltage, wherein the reference voltage is varied according to an output voltage of an output terminal of the switch circuit; and a frequency adjusting circuit, coupled to the on-time controlling circuit, configured to sense the output voltage of the output terminal of the switch circuit, generate a load sensing current according to the output voltage, and provide the load sensing current to the on-time controlling circuit for compensating the reference voltage to adjust the on-time signal of the switch circuit and a switching frequency of the switch circuit.