PFC Control Device Voltage Threshold Timing
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Solution Overview
Problem
Power supply devices with PFC circuits face the risk of degradation or damage due to instantaneous interruptions in alternating-current power supplies, and existing methods to mitigate this can lead to inadequate output voltage during abrupt changes in power supply.
Innovation Solution
A control device that compares the voltage output from a rectifier circuit with a threshold voltage and measures the time it remains below this threshold, outputting a stop signal to halt the PFC circuit operation when the time reaches a predetermined threshold, thereby preventing excessive current flow and maintaining stable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PFC circuit is operated constantly to stably supply output voltage, then the output voltage stability is improved, but the risk of degradation or damage to switching elements increases upon instantaneous interruption of alternating-current power supply
Solution Approach 1:
The control device measures the time period during which the rectified voltage remains below the threshold voltage before the actual power interruption occurs. By detecting this preliminary voltage drop pattern and timing it against a predetermined threshold, the system predicts impending power interruption and proactively stops the PFC circuit operation in advance, preventing damage to switching elements while maintaining stable output voltage during normal operation
Solution Approach 2:
The control device continuously monitors the rectified voltage level and compares it with the threshold voltage. Based on this feedback information and the measured time period, the control device dynamically adjusts the PFC circuit operation state, stopping it when the measured time exceeds the predetermined threshold and resuming when it falls below, thereby resolving the contradiction between continuous operation for stability and interruption prevention for component protection
2Object-affected harmful factors
If the PFC circuit operation is stopped to prevent switching element damage during power interruption, then the element protection is improved, but the output voltage may become inadequate during abrupt changes in power supply
Solution Approach 1:
The control device uses the measured time period of rectified voltage below threshold as a predictive indicator. By comparing this measured time against a predetermined threshold (set based on half cycle time of the lowest frequency alternating current), the system determines whether to stop or continue PFC operation, ensuring element protection while maintaining output voltage adequacy through intelligent timing-based decision making
Solution Approach 2:
The control device changes the operational state of the PFC circuit based on the parameter of measured time period. When the measured time exceeds the predetermined threshold, the PFC circuit is stopped; when it falls below, the PFC circuit continues operating. This dynamic parameter-based control resolves the contradiction by adapting the system state to the actual power supply conditions
Data Source
AI summary
There is provided a control device including a control unit, the control unit being configured to, when a first time, during which a level of a voltage output from a rectifier circuit for rectifying an alternating current supplied from an alternating-current power supply is lower than a level of a threshold voltage, has reached a threshold time, output a stop signal for stopping an operation of a power factor correction circuit to a control circuit that controls the operation of the power factor correction circuit.