Hybrid Flyback Converter Control Using Secondary Current Feedback
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Solution Overview
Problem
Current resonant hybrid flyback converters for LED-based loads lack efficiency and reliability in supplying LED lighting systems, necessitating a solution that enhances both performance metrics.
Innovation Solution
A resonant hybrid flyback converter system comprising a half-bridge circuit with high-side and low-side switches, a flyback resonant tank with a transformer, and a processing unit that senses secondary side current feedback to control switch on-times, utilizing a current transformer, shunt resistor, and lowpass filtering to ensure efficient and reliable LED load supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resonant hybrid flyback converters are used for LED-based loads, then the system can operate with basic functionality, but efficiency and reliability are insufficient
Solution Approach 1:
The patent implements a feedback mechanism where the processing unit receives feedback signals based on sensed secondary side current and uses this information to control the on-time of switches. This closed-loop control optimizes the converter operation to simultaneously improve efficiency and reliability by adjusting switching parameters based on actual load conditions
Solution Approach 2:
The patent employs dynamic control of switch on-times based on feedback signals, allowing the converter to adapt its operating parameters in real-time. The processing unit dynamically adjusts the on-time of high-side and low-side switches to optimize performance across varying load conditions, resolving the contradiction between efficiency and reliability
2Measurement precision
If secondary side current sensing is implemented to improve control precision, then efficiency increases, but device complexity increases
Solution Approach 1:
The patent introduces a current transformer as an intermediary device to sense the secondary side current. The current transformer provides isolated current sensing with high precision while maintaining galvanic isolation between primary and secondary sides. This intermediary approach achieves accurate measurement without directly complicating the main power conversion circuit
3Reliability
If multiple feedback signals and filtering components are added to improve current sensing accuracy, then reliability increases, but device complexity and cost increase
Solution Approach 1:
The patent implements lowpass filtering of the feedback signal to preliminarily remove high-frequency noise and interference before the processing unit analyzes the signal. This preliminary action of filtering ensures cleaner, more reliable current measurements without requiring overly complex signal processing circuits, thereby improving reliability while controlling 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
The system achieves a high level of efficiency and reliability by accurately sensing secondary side currents, reducing inefficiencies, and implementing safety measures to prevent overcurrent situations, thereby ensuring safe and efficient operation of the LED-based load.
Implementation Method 1
a current transformer with a first side and a second side for sensing the secondary side current
Implementation Method 2
a lowpass filtered version of the secondary side current
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A resonant hybrid flyback converter (10) for a LED-based load (13c) is provided. Said resonant hybrid flyback converter (10) comprises a half-bridge (11) comprising a high-side switch (11a) and a low-side switch (11b), a flyback resonant tank (12) comprising a transformer with a primary side (15a) and a secondary side (15b), and a processing unit (14). In this context, the half-bridge (11) is configured to supply said primary side (15a). Additionally, the secondary side (15b) is configured to supply the LED-based load (13c). Furthermore, the processing unit (14) is configured to receive at least one feedback signal based on a sensed secondary side current with respect to the secondary side (15b). Moreover, the processing unit (14) is configured to control an on-time of the low-side switch (11b) and/or an on-time of the high-side switch (11a) on the basis of the at least one feedback signal.