Three-Level Converter Heat Reduction via Switching Control
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Solution Overview
Problem
Existing power conversion apparatuses face challenges with overheating at low frequencies, increased cost due to frequency correction means, and difficulty in voltage adjustment between semiconductor devices, particularly in three-level converters.
Innovation Solution
A three-level converter configuration with specific semiconductor device and diode connections, along with a control circuit that manages the switching of these devices to minimize heat generation and achieve simultaneous ignition and extinction, allowing for efficient output voltage and reduced heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency correction means is added to protect switching semiconductor devices from overheating at low frequencies, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the frequency correction means from the system by redesigning the basic converter structure. Instead of adding a separate correction mechanism, the invention uses a fundamental restructuring of the converter topology that inherently avoids the overheating problem without requiring additional frequency correction components.
Solution Approach 2:
Rather than adding frequency correction means to fix the overheating problem, the patent inverts the approach by fundamentally changing the converter structure to prevent the problem from occurring in the first place. The conventional approach adds complexity to solve a problem, while this invention simplifies by restructuring to eliminate the root cause.
2Adaptability or versatility
If three-level converter is used to improve voltage adjustment capability, then adaptability is improved, but semiconductor devices are increased in temperature at low frequency and low modulation rate
Solution Approach 1:
The patent applies dynamic control strategies that adapt the switching patterns and modulation techniques based on operating conditions. By dynamically adjusting the control parameters and switching sequences, the system maintains effective voltage adjustment capability while preventing excessive temperature rise in semiconductor devices at low frequency and low modulation rate operations.
3Device complexity
If conventional two-level converter is used to simplify structure, then device complexity is reduced, but voltage range adjustment between semiconductor devices becomes difficult
Solution Approach 1:
The patent segments the voltage adjustment function into multiple controllable stages or levels within the converter structure. By dividing the voltage control into discrete segments or steps, the system achieves flexible voltage range adjustment while maintaining a relatively simple overall structure that avoids the complexity of conventional three-level converters.
Data Source
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AI summary
When switching control signals of self-excited semiconductor devices (G1, G2) from OFF-control to ON-control, a control circuit controls the self-excited semiconductor device (G1) to be ON after a lapse of a turn-ON time (2 × Δt) from when a control voltage is applied to the self-excited semiconductor device (G2). When switching the control signals of the self-excited semiconductor devices (G1, G2) from ON-control to OFF-control, the control circuit controls the control signal of the self-excited semiconductor device (G2) to be OFF after a lapse of a turn-OFF time (2 × Δt) from when the control voltage is applied to the self-excited semiconductor device (G1).