Transformer Current Valley Switching for Compact Power Adapters
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Solution Overview
Problem
The challenge is to reduce energy loss in power adapters without increasing their overall size, particularly in high-power density applications where heat dissipation becomes a bottleneck due to complex peripheral circuits monitoring voltage thresholds for power transistors.
Innovation Solution
A converter design with an input DC power supply, main and auxiliary power transistors, a transformer, and a controller that monitors current thresholds on the transformer to control the main power transistor's switching based on odd-numbered cycles, reducing energy loss by ensuring it turns on at valley voltage without additional circuitry, thus maintaining compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an auxiliary winding and RC circuit are added to monitor voltage for valley switching, then switching loss of the power transistor is reduced, but the peripheral circuit complexity and overall adapter size increase
Solution Approach 1:
The patent extracts the voltage monitoring function from a separate auxiliary winding and RC circuit, and integrates it into the existing transformer structure. The transformer's existing windings are utilized to provide the necessary voltage signals for valley detection, eliminating the need for additional monitoring components and reducing peripheral circuit complexity while maintaining the energy loss reduction benefit
Solution Approach 2:
The patent makes the transformer serve multiple functions: it continues to perform its primary power transformation role while simultaneously providing voltage monitoring signals for valley switching control. By utilizing the existing transformer windings for dual purposes, the design avoids adding separate monitoring circuitry, thus reducing overall device complexity while achieving low-loss switching
2Loss of energy
If an auxiliary winding and RC circuit are added to monitor voltage for valley switching, then switching loss of the power transistor is reduced, but the overall adapter size increases
Solution Approach 1:
The patent removes the need for separate voltage monitoring components (auxiliary winding and RC circuit) by extracting the monitoring function from these dedicated components and implementing it through the existing transformer structure, thereby eliminating the space these components would occupy and preventing adapter size increase
Solution Approach 2:
The patent combines the voltage monitoring function with the existing transformer structure. The transformer's windings are used both for power transformation and for providing valley detection signals, merging two functions into a single component and avoiding the need for additional space-consuming monitoring circuitry
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 effectively reduces energy loss in power transistors by ensuring they operate at valley voltage, improving efficiency without enlarging the adapter's footprint.
Implementation Method 1
a transformer, wherein the first capacitor is connected in series to the transformer to form a series circuit
Implementation Method 2
a main power transistor, an auxiliary power transistor... control the main power transistor to be turned on
Data Source
AI summary
The converter includes: an input direct current (DC) power supply, a main power transistor, an auxiliary power transistor, a first capacitor, a transformer, and a controller. The first capacitor is connected in series to the transformer to form a series circuit. The series circuit is connected in parallel to the auxiliary power transistor. A source of the main power transistor is connected to a drain of the auxiliary power transistor. A source of the auxiliary power transistor is connected to another electrode of the input DC power supply. An input negative electrode of the input DC power supply is grounded. The controller is configured to: monitor a value of a current on the transformer to obtain a quantity of times that the value of the current on the transformer reaches a specified current threshold.