Bidirectional Switch Snubber Circuit for Power Supply Efficiency
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Solution Overview
Problem
Conventional switching power supply apparatuses face issues with extra current flow through control switches, leading to incomplete turn-off of bidirectional switches and increased potential differences between terminals, which affects power conversion efficiency and miniaturization.
Innovation Solution
Incorporating a Snubber circuit with a second bidirectional switch to control the first bidirectional switch, regulating current through the primary winding of the transformer and suppressing potential differences by using a normally-off bidirectional switch and a full-wave rectifier circuit for rectification at the secondary winding side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a normally-on bidirectional switch is used with control switches to directly convert AC voltage, then power conversion efficiency is improved, but extra current flows through the control switches causing incomplete turn-off and increased potential differences
Solution Approach 1:
The patent extracts the problematic extra current flow path by introducing a snubber circuit that provides a separate discharge path for parasitic inductance current. This separates the main power conversion function from the parasitic current management, allowing the bidirectional switch to turn off completely without conducting extra current during the off-state.
Solution Approach 2:
The snubber circuit acts as an intermediary element between the bidirectional switch and the primary winding. It mediates the parasitic inductance effects by providing a controlled discharge path, preventing the parasitic current from flowing through the bidirectional switch terminals and causing potential difference issues.
2Ease of operation
If control switches are used to regulate current through the primary winding, then current control is improved, but the apparatus size increases due to additional components and larger potential differences
Solution Approach 1:
The bidirectional switch serves multiple functions: it acts as the main current control element for power conversion and simultaneously functions as part of the snubber circuit when combined with the secondary bidirectional switch. This multi-functionality eliminates the need for separate control components, maintaining compact size while achieving effective current regulation.
Solution Approach 2:
The patent merges the snubber circuit functionality with the existing bidirectional switch structure. By combining the current control function and the parasitic current management function into a unified switch-circuit system, the apparatus avoids adding separate bulky components while achieving both current control and size reduction.
3Object-affected harmful factors
If a snubber circuit is added to suppress potential differences, then switch terminal potential difference is reduced, but device complexity increases
Solution Approach 1:
Instead of adding complex active control circuits to manage potential differences, the patent inverts the approach by using a passive snubber circuit with a secondary bidirectional switch that naturally suppresses potential differences through its inherent circuit topology. This passive approach reduces complexity compared to active control solutions.
Solution Approach 2:
The snubber circuit is configured to act in advance during the switch transition period. The secondary bidirectional switch is activated to provide a discharge path for parasitic inductance before the main bidirectional switch fully turns off, preventing potential difference buildup in the first place rather than correcting it afterward.
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 configuration effectively reduces extra current flow, enhances power conversion efficiency, and allows for miniaturization of the switching power supply apparatus by controlling current flow and potential differences between switch terminals.
Implementation Method 1
a transformer including a primary winding and a secondary winding; a first bidirectional switch connected in series with the primary winding
Implementation Method 2
When the bidirectional switch is turned off, a potential difference is generated between source terminals of the bidirectional switch due to influence of parasitic inductance
Implementation Method 3
a full-wave rectifier circuit for rectification at the secondary winding side
Data Source
AI summary
A switching power supply apparatus which receives AC voltage and includes: a transformer including a primary winding and a secondary winding; a first bidirectional switch connected in series with the primary winding; and a Snubber circuit connected in parallel with the primary winding. The AC voltage is applied to a series circuit which includes the primary winding and the first bidirectional switch. The Snubber circuit includes a second bidirectional switch for controlling the first bidirectional switch.