Power Converter Switch Drive Using Auxiliary Winding Feedback
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Solution Overview
Problem
There is a need for a simple and efficient method to drive an electronic switch in a Power Factor Correction (PFC) power converter, particularly in those with galvanic isolation, to effectively regulate both output parameters and input currents.
Innovation Solution
The method involves measuring auxiliary voltages across an auxiliary winding during on-time and off-time in power converter drive cycles to obtain measurement signals, which are then used to adjust the on-time in subsequent cycles based on feedback signals, ensuring proportional input and output voltage regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional switch driving methods are used in PFC power converters with galvanic isolation, then the circuit structure is simple, but the ability to regulate both output parameters and input currents is insufficient
Solution Approach 1:
The patent implements feedback control by measuring the auxiliary voltage across the auxiliary winding during both on-time and off-time, processing these measurements through operational amplifiers to generate feedback signals, and using these signals to adjust the on-time duration in subsequent drive cycles. This closed-loop feedback mechanism enables precise regulation of both output parameters and input currents while maintaining proportional relationship between them.
Solution Approach 2:
The patent replaces direct mechanical or simple electronic control of the switch with an intelligent control method that uses voltage measurements and signal processing. Instead of direct control, the system uses operational amplifiers to process voltage measurements and generate appropriate feedback signals that automatically adjust the on-time, substituting complex control logic with analog signal processing.
2Measurement precision
If the on-time is adjusted based on multiple measurement parameters, then the regulation precision is improved, but the measurement and control complexity increases
Solution Approach 1:
The auxiliary winding serves multiple functions: it provides voltage measurement during on-time for one feedback signal, provides voltage measurement during off-time for another feedback signal, and both signals are used together to control the on-time adjustment. This multi-functional use of a single component reduces overall system complexity while achieving precise regulation.
Solution Approach 2:
The patent introduces operational amplifiers as intermediary components that process the raw voltage measurements from the auxiliary winding. These intermediaries convert the measured voltages into standardized feedback signals that can be directly used for on-time adjustment, simplifying the control logic while maintaining measurement precision.
3Productivity
If the on-time is extended to transfer more energy, then the power conversion efficiency is improved, but the risk of core saturation and loss of control increases
Solution Approach 1:
The on-time duration is made dynamic rather than fixed. The control method automatically adjusts the on-time in each drive cycle based on real-time feedback from voltage measurements. This dynamic adjustment allows the system to extend on-time when needed for efficient energy transfer while automatically reducing it when approaching saturation, maintaining both efficiency and reliability.
Solution Approach 2:
The system performs preliminary measurements of the auxiliary voltage during both on-time and off-time before determining the optimal on-time for the next cycle. This preliminary action allows the control system to anticipate and prevent core saturation by adjusting the on-time based on measured conditions, ensuring reliable operation while maximizing efficiency.
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 allows for precise control of the electronic switch, enhancing the power converter's ability to regulate output parameters and align input currents with input voltages, thereby improving power factor correction efficiency.
Implementation Method 1
measuring an auxiliary voltage across the auxiliary winding during the on-time in a drive cycle
Data Source
AI summary
A method and a control circuit for driving an electronic switch coupled to an inductor in a power converter in successive drive cycles each including an on-time and an off-time are disclosed. Driving the electronic switch includes: measuring an inductor voltage during the on-time in a drive cycle in order to obtain a first measurement value; measuring the inductor voltage during the off-time in a drive cycle in order to obtain a second measurement value; obtaining a first voltage measurement signal that is dependent on a sum of the first measurement value and the second measurement value; and adjusting the on-time in a successive drive cycle dependent on a feedback signal and the first voltage measurement signal.