Isolated Power Converter Controller With Bypass Capacitor Charging
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Solution Overview
Problem
Conventional isolated switched-mode power supplies are sensitive to output voltage undervoltage conditions and switching frequency variations, leading to inefficiencies and unreliable power supply.
Innovation Solution
A controller is introduced with a bypass terminal coupled to a bypass capacitor, and power circuits that transfer charge to the capacitor based on voltage thresholds, controlled by a charging control circuit to maintain stable power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power is supplied by output voltage Vout, then charging efficiency is high, but VCC experiences undervoltage condition when output voltage drops
Solution Approach 1:
A bypass capacitor is introduced as an intermediary energy storage element between the power supply and the controller. The capacitor decouples the controller from direct voltage fluctuations, providing stable power during transient conditions and preventing undervoltage lockout while maintaining high charging efficiency.
2Reliability
If power is supplied by voltage Forw across secondary-side winding, then undervoltage protection is provided, but charging efficiency is low and VCC experiences undervoltage at low switching frequency
Solution Approach 1:
The power supply system transitions from a static, frequency-dependent voltage source to a dynamic, frequency-independent capacitor-based supply. The bypass capacitor dynamically adapts to varying switching frequencies and load conditions, maintaining stable VCC voltage regardless of frequency changes or undervoltage conditions.
3Use of energy by moving object
If dual power supply (Forw and Vout) is used, then high efficiency is achieved, but system becomes sensitive to undervoltage when both output voltage and switching frequency are low
Solution Approach 1:
The system extracts and isolates the voltage stabilization function from the dual power supply configuration by introducing a dedicated bypass capacitor. This separates the energy storage function from the power conversion function, allowing the controller to operate independently of voltage fluctuations and undervoltage conditions while maintaining high charging 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
The solution ensures high charging efficiency and reduces sensitivity to output voltage fluctuations and switching frequency variations, providing a stable power supply.
Implementation Method 1
a bypass terminal coupled to a bypass capacitor which is in turn coupled to a secondary side of an isolated power converter
Implementation Method 2
a first power circuit coupled to transfer electric charge from the first terminal to the bypass terminal so that it is stored in the bypass capacitor
Implementation Method 3
a second power circuit coupled to transfer the electric charge from the first terminal to the flying capacitor and from the flying capacitor to the bypass terminal so that it is stored in the bypass capacitor
Data Source
AI summary
A controller and an isolated power converter are disclosed. The controller includes: a bypass terminal coupled to a bypass capacitor; a first power circuit coupled to the bypass terminal and a first terminal, the first terminal configured to transfer electric charge from the first terminal to the bypass terminal; a second power circuit coupled to the first terminal, a second terminal and a third terminal, the second and third terminals coupled to a flying capacitor, the second power circuit configured to transfer electric charge from the first terminal to the flying capacitor; and a charging control circuit coupled to control the first or second power circuit to transfer electric charge to the bypass terminal, in response to at least one of a voltage at the bypass terminal and a voltage at the first terminal. The present invention eliminates influence of switching frequency variation and reduces sensitivity to an output voltage.