Totem-Pole PFC Switch Control for Low-Voltage Hard Turn-On
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Solution Overview
Problem
The hard turn-on of switching transistors in totem-pole power factor correction circuits leads to increased switching losses due to voltage differences at both sides of the auxiliary power switch when the input voltage is low, affecting the efficiency of the power module.
Innovation Solution
A control circuit is implemented to manage the turn-on and turn-off of main and auxiliary power switches based on input voltage phase and absolute value, ensuring the auxiliary power switch remains off when the voltage is low and alternates with the main power switch when necessary, thereby reducing switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the auxiliary power switch is turned on during low input voltage phases, then the circuit can maintain continuous operation, but hard turn-on occurs causing increased switching losses
Solution Approach 1:
The control circuit detects low voltage phases in advance and prevents the auxiliary power switch from turning on during these phases. By taking preliminary action to identify when voltage is below the threshold, the system avoids the harmful hard turn-on condition before it can occur, thereby reducing switching losses while maintaining reliable operation during appropriate voltage phases
Solution Approach 2:
The operating state of the auxiliary power switch is dynamically adjusted based on real-time detection of input voltage phases. The switch is enabled during high voltage phases and disabled during low voltage phases, creating a dynamic control strategy that adapts to changing voltage conditions to minimize switching losses while ensuring continuous circuit operation
2Use of energy by moving object
If the control circuit adjusts charging and discharging time of the inductor to change power factor, then power consumption efficiency is improved, but control complexity increases
Solution Approach 1:
The control circuit employs feedback mechanisms to monitor the input voltage waveform and automatically adjusts the charging and discharging timing of the inductor accordingly. This feedback-based control enables the system to optimize power factor and improve power consumption efficiency by synchronizing switch operations with the voltage waveform, while the automated nature of the feedback loop prevents excessive control complexity
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
This approach reduces switching losses and improves the operating efficiency of the totem-pole power factor correction circuit and the power module by avoiding hard turn-on of the auxiliary power switch, maintaining a simple circuit structure and low costs.
Implementation Method 1
When alternately charged and discharged, the inductor may be configured to rectify the alternating current, and provide the input voltage for the direct current conversion circuit
Implementation Method 2
The control circuit is configured to control turn-on and turn-off of the at least one switching transistor, to alternately charge and discharge the inductor
Data Source
AI summary
A power module, a totem-pole power factor correction circuit, and a control circuit thereof. In response to a case in which a phase value of a transient voltage of an input voltage of the totem-pole power factor correction circuit is within a predetermined phase range, and an absolute value of a voltage value is less than a predetermined voltage value, the control circuit controls a main power switch in the totem-pole power factor correction circuit to be turned on and off, and controls an auxiliary power switch to remain off.