Self-Oscillating Power Converter with Current Transformer Feedback
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Solution Overview
Problem
Existing power converters face challenges in achieving high efficiency and low no-load power consumption while being cost-effective and simple, often resulting in complex designs with mass production issues.
Innovation Solution
A push-pull type power converter that is self-driven by its output current, using a main power transformer and a current transformer with switching transistors to minimize drive circuit losses and automatically control dead-time, ensuring efficient operation and low no-load power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If complex resonant type converters are used to improve efficiency and reduce stand-by power consumption, then power conversion efficiency is improved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent implements self-service by using the output current of the converter itself as the reference for the drive current of the switching transistors. This eliminates the need for external control circuits, sense resistors, and complex feedback mechanisms. The output current directly controls the switching action through the current transformer, making the system self-regulating and highly efficient while remaining simple in structure.
2Use of energy by stationary object
If complex resonant type converters are used to reduce no-load power consumption, then stand-by power consumption is reduced, but manufacturing cost increases
Solution Approach 1:
The self-service principle reduces no-load power consumption by automatically stopping switching when no or low output currents are drawn. The output current itself controls the switching transistors through the current transformer, so when load is removed, the switching action ceases naturally without requiring complex control circuits or additional components.
Solution Approach 2:
The patent extracts and eliminates unnecessary control circuitry, sense resistors, and complex feedback mechanisms from the design. By using the output current directly as the drive reference, it removes the disturbing parts that would otherwise consume power during stand-by conditions, achieving simplicity and low cost.
3Reliability
If automatic dead-time control is implemented to prevent simultaneous conduction, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent achieves automatic dead-time control through self-service without external control circuits. When one switching transistor conducts, it generates current through the main transformer that is transformed by the current transformer to drive the other transistor into conduction. This natural coupling through magnetic fields provides automatic timing and dead-time control, ensuring reliable operation while maintaining simplicity.
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 achieves high efficiency, especially at low loads, and reduces no-load power consumption through automatic switching control, with the converter stopping operation when no output current is drawn, and using bi-polar switching elements for surge resistance.
Implementation Method 1
a current drive transformer to transform the output current back to a primary current to drive the transistors
Implementation Method 2
a main power transformer with a primary side and a secondary side respectively connected in series to a primary side and a secondary side of a current transformer
Implementation Method 3
two NPN power BJT transistors as switching transistors
Data Source
AI summary
A push-pull type self-oscillating power converter uses a main power transformer connected to a current transformer in series in such a way that a secondary current flowing through secondary sides of the two transformers is feedback to the primary side of the current drive transformer to generate a drive current for driving two switches. The drive current is proportional to the secondary current in the secondary side of the main power transformer.