LED Power Converter OVP Using Demagnetization Voltage Sampling
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Solution Overview
Problem
Conventional power conversion systems with primary-side regulation (PSR) and buck-boost mechanism lack precise output voltage measurement, leading to inadequate overvoltage protection (OVP) and potential damage to output capacitors.
Innovation Solution
A system controller for a power converter is introduced, featuring a logic controller, driver, voltage-to-voltage converter, and comparator. This controller generates a modulation signal to control the switch's on-time and demagnetization periods, allowing for precise output voltage regulation and overvoltage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional PSR power conversion systems are used, then device complexity is reduced, but output voltage measurement precision deteriorates leading to inadequate overvoltage protection
Solution Approach 1:
The patent introduces an intermediary measurement mechanism that samples the voltage across the inductive winding during the demagnetization period. This intermediary approach allows the system to indirectly obtain output voltage information without requiring direct secondary-side measurement, thus maintaining primary-side regulation simplicity while achieving precise overvoltage detection
Solution Approach 2:
The patent implements a feedback mechanism where the sampled voltage during demagnetization is compared against reference thresholds to generate overvoltage protection signals. This feedback loop enables the controller to continuously monitor and respond to output voltage conditions, achieving precise measurement and protection without complicating the overall system structure
2Device complexity
If single inductive winding is used, then device complexity is reduced, but overvoltage protection capability deteriorates
Solution Approach 1:
The patent applies preliminary action by sampling the inductive winding voltage during the demagnetization period before potential overvoltage damage can occur. This advance measurement allows the system to detect overvoltage conditions early and trigger protection mechanisms preemptively, enhancing reliability without adding secondary windings
Solution Approach 2:
The patent utilizes the brief demagnetization period to rapidly sample the voltage and make protection decisions. By rushing through the measurement during this critical window, the system achieves timely overvoltage detection and response, maintaining reliability with a single inductive winding
Data Source
AI summary
System controller and method for a power converter. For example, a system controller for a power converter includes a logic controller configured to generate a modulation signal, and a driver configured to receive the modulation signal, generate a drive signal based at least in part on the modulation signal, and output the drive signal to a switch to affect a current flowing through an inductive winding for a power converter. Additionally, the system controller includes a voltage-to-voltage converter configured to receive a first voltage signal, the modulation signal, and a demagnetization signal, and to generate a second voltage signal based at least in part on the first voltage signal, the modulation signal, and the demagnetization signal.