Switching Power Supply Dynamic On-Time Control
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Solution Overview
Problem
Non-linear control type switching power supply devices experience significant variations in switching frequency with input voltage, output voltage, and output current, leading to poor output voltage accuracy and load regulation, making them unsuitable for applications with large input voltage variations or multiple output voltages, and they also face challenges in preventing electromagnetic interference (EMI) and noise.
Innovation Solution
A switching power supply device with a non-linear control type switching control unit, a backflow current detection unit, and an on-time setting unit that adjusts the on-time of the switch element based on feedback voltage and switch voltage, allowing for stable output voltage generation and reduced switching frequency variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-linear control type switching power supply device is used, then high load response characteristic can be obtained with simple circuit configuration, but switching frequency varies largely with input voltage, output voltage, and output current leading to poor output voltage accuracy and load regulation characteristic
Solution Approach 1:
The patent applies dynamics by making the on-time of the switching element variable rather than fixed. The control unit adjusts the on-time based on detected output voltage and current values, allowing the switching frequency to be stabilized while maintaining the simplicity of non-linear control. This dynamic adjustment resolves the contradiction by enabling both fast load response and accurate output voltage regulation.
Solution Approach 2:
The patent implements feedback control by detecting the output voltage and current values, comparing them with reference values, and adjusting the on-time accordingly. This feedback mechanism allows the system to maintain accurate output voltage and load regulation while preserving the fast response characteristics of non-linear control, directly resolving the technical contradiction.
2Device complexity
If non-linear control type switching power supply device is used, then simple circuit configuration is achieved, but load regulation characteristic (stability of output voltage with respect to load variation) is poor
Solution Approach 1:
The patent makes the on-time dynamic by adjusting it based on detected output conditions. This allows the simple non-linear control configuration to achieve stable load regulation, as the on-time varies to compensate for load changes while maintaining circuit simplicity.
Solution Approach 2:
The patent uses feedback from detected output voltage and current to adjust the on-time, enabling the simple circuit to achieve stable load regulation. The feedback loop compensates for load variations without adding complex circuitry, resolving the contradiction between simplicity and stability.
3Object-affected harmful factors
If measures are taken to prevent EMI and noise in non-linear control type switching power supply, then electromagnetic interference is suppressed, but set designing becomes difficult
Solution Approach 1:
The patent replaces mechanical/physical EMI filtering components with an electronic control solution. By stabilizing switching frequency through dynamic on-time adjustment based on feedback, the system suppresses EMI and noise without requiring complex physical filtering circuits, making set design easier while maintaining EMI suppression.
Data Source
AI summary
A switching power supply device includes: a non-linear control type switching control unit that, in accordance with a result of a comparison between a feedback voltage and a reference voltage, performs on/off control of a switch element, and thereby generates an output voltage from an input voltage; a backflow current detection unit that, upon detecting a backflow current flowing to the switch element, forcibly switches off the switch element; and an on-time setting unit that sets an on-time of the switch element, in a case of the backflow current not being detected, in accordance with a duty of the switch element, and in a case of the backflow current being detected, in accordance with a switch voltage appearing at one end of the switch element or the output voltage.