Power Factor Correction Circuit Short Circuit Detection
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Solution Overview
Problem
Conventional power factor correction circuits face difficulties in sensing auxiliary coil short circuits, leading to increased temperature and potential damage due to overcurrent, as they struggle to differentiate between short circuits and normal operating conditions.
Innovation Solution
A power factor correction circuit with an auxiliary coil and a controller that counts the number of times the inductor current reaches a maximum current threshold, using a counter and D-flipflop to generate a disable signal when the threshold is reached, allowing for precise detection of short circuits and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the auxiliary coil is used for zero current detection, then the switching operation can be controlled accurately, but the auxiliary coil may be short-circuited causing inductance decrease and overcurrent
Solution Approach 1:
The patent introduces a sensing coil as an intermediary element that magnetically couples with the auxiliary coil without direct electrical contact. This allows the detection of auxiliary coil short circuits through magnetic field changes while preventing direct current flow that would cause short circuits. The sensing coil acts as a mediator between the auxiliary coil and the control circuit.
Solution Approach 2:
The patent replaces the direct electrical connection method with a magnetic coupling method. Instead of using electrical contacts to detect auxiliary coil status, the system uses magnetic field sensing through the sensing coil, which eliminates the risk of electrical short circuits while maintaining detection capability.
2Reliability
If the maximum current is set for protection, then the switch current can be controlled within safe limits, but it is difficult to control protection when input voltage decreases after peak current is reached
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the auxiliary coil's magnetic field through the sensing coil. This feedback allows the control circuit to detect changes in auxiliary coil status and adjust protection control accordingly, enabling adaptive protection that responds to varying input voltage conditions while maintaining switch current within safe limits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise sensing of auxiliary coil short circuits, preventing overheating and damage by accurately distinguishing between short circuits and normal conditions, thereby ensuring safe operation.
Implementation Method 1
The power factor correction circuit senses a time point when the inductor current becomes zero using an auxiliary coil coupled to the inductor
Implementation Method 2
an inductor receiving an input voltage and supplying output power
Data Source
AI summary
The present invention relates to a power factor correction circuit and a driving method thereof. The power factor correction circuit refers to an inductor receiving an input voltage and supplying output power, a power switch connected to the inductor and controlling an inductor current flowing in the inductor, and an auxiliary coil coupled with the inductor with a predetermined turn ratio. The power factor correction circuit controls the output power by controlling a switching operation of the power switch, and counts the number of times that the inductor current reaches a predetermined maximum current to turn off the power switch when the count result reaches a predetermined short circuit threshold count.