Synchronous Rectifier Auxiliary Control Circuit
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Solution Overview
Problem
Conventional self-driving synchronous rectifying apparatuses experience shoot-through problems due to instantaneous short circuits in the secondary winding of the transformer, leading to additional power loss and electromagnetic interference, which affect the efficiency of DC-DC converters.
Innovation Solution
The introduction of an auxiliary control module with an auxiliary switch and winding, controlled by the PWM control circuit to turn off the synchronous rectifier before the transfer switch is turned on, preventing shoot-through and reducing power loss and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If self-driving synchronous rectifying is used to reduce component count and cost, then device complexity and cost are reduced, but shoot-through problems occur causing additional power loss and electromagnetic interference
Solution Approach 1:
The patent applies preliminary action by introducing an auxiliary control circuit that proactively turns off the synchronous rectifier before the transfer switch turns on. This preventive measure eliminates the shoot-through problem before it can occur, resolving the contradiction between using simple self-driving rectifying and avoiding power loss from shoot-through events.
Solution Approach 2:
The patent introduces an auxiliary control circuit as an intermediary between the PWM control circuit and the synchronous rectifier. This intermediary component coordinates the switching timing to prevent shoot-through, allowing the system to maintain simple self-driving architecture while eliminating the harmful effects that would otherwise occur.
2Ease of operation
If self-driving synchronous rectifying is used to simplify circuit arrangement, then ease of operation is improved, but shoot-through causes electromagnetic interference
Solution Approach 1:
The auxiliary control circuit performs preliminary action by preemptively turning off the synchronous rectifier before the transfer switch activates. This prevents shoot-through and the associated electromagnetic interference while preserving the simplicity of the self-driving circuit arrangement.
Solution Approach 2:
The auxiliary control circuit serves as an intermediary that coordinates switching operations to prevent electromagnetic interference. It maintains the simple self-driving architecture while eliminating the harmful electromagnetic effects through proper timing control.
3Duration of action of stationary object
If synchronous rectifier remains on during transfer switch turn-on, then continuous conduction is maintained, but instantaneous short circuit occurs reducing efficiency
Solution Approach 1:
The auxiliary control circuit applies preliminary action by turning off the synchronous rectifier before the transfer switch turns on. This prevents the instantaneous short circuit that would occur from overlapping conduction, resolving the contradiction between maintaining continuous conduction and avoiding efficiency-reducing short circuits.
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 solution efficiently addresses the shoot-through problem, minimizing power loss and electromagnetic interference, thereby enhancing the efficiency of the DC-DC converter.
Implementation Method 1
an auxiliary control module including at least one auxiliary control circuit and at least one auxiliary winding, wherein the auxiliary control circuit includes at least one auxiliary switch, the auxiliary control circuit being electrically coupled to the Pulse Width Modulation control circuit and the auxiliary winding via the auxiliary switch, the auxiliary winding being electrically coupled to the transformer
Data Source
AI summary
The present application provides a synchronous rectifying apparatus and a control method thereof, the apparatus comprising: a transformer, a primary circuit, a rectifying circuit, a self-driving circuit, a PWM control circuit and an auxiliary control module including at least one auxiliary control circuit and at least one auxiliary winding, wherein the auxiliary control circuit includes at least one auxiliary switch and is electrically coupled to the Pulse Width Modulation control circuit and the auxiliary winding via the auxiliary switch, and the auxiliary winding is electrically coupled to the transformer; wherein before the transfer switch of the primary circuit is controlled to be turned on by the switching control signal, the auxiliary switch is controlled to be turned on by the auxiliary control signal, and the synchronous rectifier of the rectifying circuit is controlled to be turned off through the self-driving signal.