Multi-Level Converter Segmentation for UPS Efficiency
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Solution Overview
Problem
Converter devices for high-power uninterruptible power supplies face inefficiencies due to high power losses in static switches that can withstand large voltages and require high-frequency switching, leading to increased energy losses and component stress.
Innovation Solution
A multi-level converter device with separate switching units for positive and negative voltage alternations, each comprising a maximum, intermediate, and minimum voltage branch with specific switching groups and permutation means like thyristors and diodes, allowing for reduced switching frequency and lower holding voltages, thereby minimizing energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If static switches capable of withstanding large voltages are used in high-power uninterruptible power supplies, then the device can handle high voltage levels, but power losses increase significantly
Solution Approach 1:
The patent divides the voltage conversion process into multiple stages with separate switching units for positive and negative voltage alternations. Each unit handles only a portion of the voltage range, allowing the use of switches with lower voltage ratings while maintaining overall high voltage capability. This segmentation reduces the voltage stress on individual switches and consequently lowers power losses.
Solution Approach 2:
The invention changes the operating parameters by using switches rated for lower holding voltages in a multi-level configuration. Instead of using a single high-voltage switch, the system uses multiple switches operating at lower voltage levels, which reduces the conduction losses and improves overall efficiency while still handling high power applications.
2Speed
If high-frequency switching is used to improve converter performance, then the response speed and control precision improve, but energy losses and component stress increase
Solution Approach 1:
By segmenting the switching operation into separate units handling positive and negative alternations, each unit operates at optimized frequency levels. This allows for effective voltage control without requiring excessively high switching frequencies across the entire system, thereby reducing energy losses while maintaining adequate response speed.
3Device complexity
If a single switching unit handles both positive and negative voltage alternations, then the device structure is simpler, but the switching components experience higher stress and require higher holding voltages
Solution Approach 1:
The patent explicitly segments the switching function into separate units: one for positive voltage alternations and another for negative voltage alternations. Each unit requires switches rated for lower holding voltages corresponding to their specific voltage range, rather than requiring a single unit with switches capable of withstanding the full voltage swing. This reduces component stress and allows for more efficient component selection.
Data Source
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AI summary
The device (21) has switching units (UC1, UC2) for converting series of positive and negative alternating cut-off voltage (VA) into positive and negative direct voltage levels, respectively. The switching units are connected to a reference voltage line (5) and to direct voltage lines (6-9). The switching units have respective cutting points (S1, S2) that are connected to a cut-off voltage point (3) by switch-over units (23). Switching groups (41-46) are connected between lines to which the switching units are connected, and the cutting points, respectively. An independent claim is also included for an uninterruptible power supply comprising an inverter.