PWM Controller Overload Circuit Dynamics

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Solution Overview

Problem

Existing PWM power supply controllers inefficiently handle small power overloads and fail to accurately sense power overload conditions, leading to potential damage to components.

Innovation Solution

A PWM controller with an overload circuit that senses the output voltage and inhibits the drive signal for a duration inversely proportional to the power required by the load, preventing damage by terminating power supply when the load exceeds rated capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the controller terminates power supply immediately upon detecting overload condition, then the controller protects itself from damage, but the controller cannot efficiently handle small power overloads

Engineering Contradiction:
Improvecontroller protectionVSAvoidhandling small power overloads
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the controller's response adaptive rather than static. The overload response time is dynamically adjusted based on the severity of the overload condition. For small overloads, the controller allows extended operation with gradual power reduction, while for severe overloads, it implements immediate termination. This dynamic response enables the controller to handle both small and large power overloads efficiently while maintaining self-protection.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If the controller uses simple overload detection, then the device complexity is reduced, but the measurement precision of power overload condition is insufficient

Engineering Contradiction:
Improvecontroller structureVSAvoidpower overload sensing
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements feedback mechanisms to improve measurement precision without significantly increasing device complexity. The controller continuously monitors output voltage and compares it against reference values to detect overload conditions. The feedback loop provides real-time information about the power delivery status, enabling accurate detection of both small and large overloads. This feedback-based approach achieves precise measurement while maintaining a relatively simple controller structure.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If the controller regulates power for extended period during overload, then the controller handles small overloads more efficiently, but the controller may be damaged by sustained high power delivery

Engineering Contradiction:
Improvehandling small power overloadsVSAvoidcontroller protection
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses dynamics to create a time-varying response to overload conditions. When an overload is detected, the controller dynamically adjusts the power delivery duration based on the overload severity. For small overloads, the controller extends the regulation period to allow gradual power reduction, while for severe overloads, it implements immediate termination. This dynamic time-based control enables the controller to protect itself from damage while efficiently handling small power overloads.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS7961485B2Method of forming a PWM controller and structure therefor
Publication Date: 2011.06.14 SEMICON COMPONENTS IND LLC
  • US7961485B2 patent drawing
  • US7961485B2 patent drawing
  • US7961485B2 patent drawing

AI summary

In one embodiment, a PWM controller is configured to inhibit forming a drive signal responsively to an overload sense signal having a value that is no greater than a first value for a first time interval and to form a first duration of the first time interval responsively to the overload sense signal.