Converter Pulse Blocking for Transformer Secondary Overvoltage

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Solution Overview

Problem

The existing converters face damage to switching transistors due to overvoltage during pulse blocking protection, as inductor current continues to flow through parasitic capacitors without a freewheeling loop, leading to significant voltage surges.

Innovation Solution

A pulse blocking method that includes turning off switching transistors in the primary circuit first and then in the secondary circuit at zero-crossing points or forming a freewheeling loop to prevent current from flowing through parasitic capacitors, thereby avoiding overvoltage damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If all switching transistors are turned off directly during pulse blocking protection, then shutdown response is fast, but voltage surge occurs on parasitic capacitor causing transistor damage

Engineering Contradiction:

Improveshutdown response speedVSAvoidswitching transistor reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by detecting the current state of the inductive device before turning off switching transistors. When current is detected, the system prepares alternative current paths (first or second circuit) in advance, and only turns off transistors when current reaches zero, preventing voltage surge while maintaining fast response

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary control mechanism that monitors inductive device current and mediates the switching transistor shutdown process. The controller acts as an intermediary, coordinating between the shutdown command and the actual transistor switching, ensuring transistors are turned off only when safe (at zero current points) to prevent overvoltage damage

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If switching transistors are turned off in batches with current monitoring, then transistor damage is avoided, but control complexity increases

Engineering Contradiction:

Improveswitching transistor protectionVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the switching transistor shutdown into staged batches rather than simultaneous or individual switching. Transistors are grouped and turned off in sequences (first batch, then second batch) based on current monitoring, simplifying the control logic while ensuring reliable protection against overvoltage damage

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250317049A1Converter and chopper transistor blocking control method therefor

Publication Date: 2025.10.09 SUNGROW POWER SUPPLY CO LTD

AI summary

The present application provides a converter and a chopper transistor blocking control method therefor. According to the chopper transistor blocking control method, when switching transistors in a converter need to be blocked, switching transistors in a primary side circuit connected to a transformer of the converter are blocked, and switching transistors in a secondary side circuit are blocked when the current on a branch where a secondary side winding in the transformer is located is zero, or batch blocking of the switching transistors in the secondary side circuit is completed after the current on the branch where the secondary side winding is located recirculates to zero, thereby avoiding overvoltage damage to the switching transistors caused by the current on the branch where the secondary side winding is located recirculating by means of the junction capacitance of the switching transistors in the secondary side circuit.