Cascaded MOSFET Flyback VCC Supply Without Auxiliary Winding
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Solution Overview
Problem
Conventional VCC charging circuits in flyback converters face inefficiencies due to the inclusion of an auxiliary winding, which increases costs, complexity, and reduces efficiency, while also forcing the IC power supply voltage outside its operating range, especially under varying output voltages.
Innovation Solution
A VCC charging circuit that generates power supply voltage without an auxiliary winding, utilizing a flyback topology separate from the main circuit, with either pre-bridge or post-bridge coupling to the diode bridge, allowing direct sensing and regulation of the AC input voltage for improved efficiency and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary winding is included in the flyback converter, then the power supply voltage can be generated, but the device complexity and cost increase
Solution Approach 1:
The patent removes the auxiliary winding from the transformer, extracting the problematic component that caused complexity and cost issues. The power supply voltage generation function is retained by using the primary winding in conjunction with a secondary transistor to create a cascaded MOSFET configuration that eliminates the need for the auxiliary winding.
Solution Approach 2:
The patent combines the power supply voltage generation function with the main power conversion function by using the same primary winding for both purposes. The cascaded MOSFET configuration merges the auxiliary power generation role into the existing primary circuit, eliminating the need for separate auxiliary components.
2Reliability
If an auxiliary winding is included in the flyback converter, then the power supply voltage can be generated, but the manufacturing cost increases
Solution Approach 1:
The patent removes the auxiliary winding from the transformer, extracting the problematic component that caused complexity and cost issues. The power supply voltage generation function is retained by using the primary winding in conjunction with a secondary transistor to create a cascaded MOSFET configuration that eliminates the need for the auxiliary winding.
Solution Approach 2:
The primary winding is designed to serve dual functions: main power conversion and auxiliary power supply voltage generation. This multi-functionality eliminates the need for separate auxiliary components, reducing part count and manufacturing cost while maintaining the required power generation capability.
3Reliability
If an auxiliary winding is included in the flyback converter, then the power supply voltage can be generated, but the efficiency decreases
Solution Approach 1:
The patent combines the power supply voltage generation function with the main power conversion function by using the same primary winding for both purposes. The cascaded MOSFET configuration merges the auxiliary power generation role into the existing primary circuit, eliminating the need for separate auxiliary components.
Solution Approach 2:
The primary winding serves itself by providing both main power conversion and auxiliary power supply voltage generation. The cascaded MOSFET configuration allows the primary circuit to generate the required power supply voltage for the controller IC without requiring separate auxiliary components, reducing overall system losses.
4Adaptability or versatility
If the output voltage varies, then the converter can adapt to different conditions, but the IC power supply voltage goes outside operating range
Solution Approach 1:
The patent implements a feedback mechanism where the controller IC monitors the power supply voltage and adjusts the duty cycle of the primary MOSFET accordingly. This feedback control ensures that the power supply voltage remains within the operating range of the controller IC even when the output voltage varies, maintaining reliable operation across different conditions.
Solution Approach 2:
The cascaded MOSFET configuration provides dynamic control of the power supply voltage through the secondary transistor, which is controlled by the controller IC. This dynamic adjustment capability allows the system to maintain stable power supply voltage to the controller IC while adapting to varying output voltage conditions through real-time duty cycle modulation.
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 enhances efficiency, reduces costs, and maintains the IC power supply voltage within the operating range by eliminating the need for an auxiliary winding, enabling better power factor correction and fault detection, and minimizing noise and oscillations.
Implementation Method 1
a transformer including a primary winding and a secondary winding
Implementation Method 2
a power supply voltage capacitor having a positive terminal coupled to the secondary winding and having a negative terminal coupled to ground
Data Source
AI summary
A system is provided that includes a diode bridge for rectifying an AC input voltage. A main switching power converter converts a rectified input voltage from the diode bridge into an output voltage. A flyback converter is coupled either to a pre-bridge node or a post-bridge node to receive an input voltage that is converted into a power supply voltage for a controller integrated circuit. The controller integrated circuit regulates both the output voltage and the power supply voltage.