Overvoltage Repetition Prevention Circuit for Power Factor Correction
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Solution Overview
Problem
Power factor correction circuits experience repeated overvoltage issues due to slow control response, leading to repeated overvoltage protection operations when input voltage changes or load conditions alter, causing output voltage to exceed threshold.
Innovation Solution
An overvoltage repetition prevention circuit is introduced, which includes a power factor correction controller that switches to a proportional control structure during an overvoltage stabilization period, generating a control voltage proportional to the output voltage error, and includes a current detector, current mirror, I/V converter, and control switch to prevent overvoltage recurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slow control loop speed is used to maintain constant output voltage and control input current to follow sine wave, then power factor correction is achieved, but the control response becomes too slow to prevent overvoltage recurrence
Solution Approach 1:
The control loop dynamically switches between two modes: normal proportional-integral control for power factor correction, and overvoltage protection mode with forced switching stop when overvoltage occurs. This dynamic adaptation allows the system to maintain reliable power factor correction under normal conditions while rapidly responding to overvoltage events by forcing a stop, thus resolving the contradiction between slow control speed and overvoltage prevention capability
2Object-affected harmful factors
If overvoltage protection operation is triggered to stop switching when output voltage exceeds threshold, then overvoltage is protected, but the protection operation repeats continuously due to slow feedback voltage response
Solution Approach 1:
The system performs preliminary detection of overvoltage conditions and immediately executes a forced stop of switching operations before the overvoltage can cause damage. By anticipating the harmful effect and acting in advance, the system prevents overvoltage recurrence without continuous repetition of protection operations, thus resolving the contradiction between protection effectiveness and time loss
Data Source
AI summary
The present invention relates to an overvoltage repetition prevention circuit, a method thereof, and a power factor correction circuit including the same. The power factor correction circuit includes: an inductor receiving an input voltage and supplying an output voltage; a power switch connected to the inductor and controlling an inductor current to the inductor; and a power factor correction controller differently controlling a control structure generating a control voltage controlling a switching operation of the power switch during a predetermined overvoltage stabilization period generated in synchronization with a time that an output voltage is an overvoltage and the control structure generating the control voltage in a normal state in which the output voltage is not the overvoltage, wherein the control structure is determined according to a difference between the output voltage and a predetermined output target voltage during the overvoltage stabilization period.