T-Type Power Converter With Adjustable DC-Link Voltage Ratio
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Solution Overview
Problem
Conventional 2-level power converters have limited output voltage ranges and inefficiencies due to fixed intermediate circuit voltages, leading to restricted applications and increased harmonics, which necessitate larger and more costly filters.
Innovation Solution
A 2-phase 3-level T-type power converter with adjustable intermediate circuit voltages, utilizing a bidirectional center switch and an evaluation unit for space vector modulation, allowing flexible voltage ratio adjustment and expanded output range without additional components, reducing conduction losses and enabling fault-tolerant operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a 2-level power converter is used, then the device complexity is reduced, but the output voltage range is limited and harmonics increase
Solution Approach 1:
The DC link voltage is segmented into two separate intermediate circuit capacitors (first and second intermediate circuit capacitors) with adjustable voltage ratios. This segmentation allows independent control of voltage levels, enabling the converter to achieve a broader output voltage range while maintaining a simplified 2-level topology without requiring additional switching stages
Solution Approach 2:
The invention dynamically adjusts the voltage ratio between the first and second intermediate circuit capacitors based on the required output voltage. By changing the voltage parameters of the intermediate capacitors rather than the converter topology, the system achieves variable output voltage range while keeping the device structure simple and avoiding the complexity of multi-level converters
2Device complexity
If a 2-level power converter is used, then the device structure is simplified, but harmonics in the output signal increase
Solution Approach 1:
By dynamically adjusting the voltage ratio between the two intermediate circuit capacitors, the invention modifies the effective switching voltage levels available to the converter. This parameter change enables better control over the output voltage waveform, reducing harmonic content while maintaining the simple 2-level switching structure and avoiding the need for complex multi-level topologies
3Device complexity
If intermediate circuit voltages are fixed, then the converter structure is simplified, but the output voltage range is restricted
Solution Approach 1:
The invention introduces dynamic control of the intermediate circuit voltages through an evaluation unit that adjusts the voltage ratio between the first and second intermediate circuit capacitors based on the required output voltage. This dynamic adjustment capability allows the converter to adapt its output voltage range to different operating conditions while keeping the physical converter structure relatively simple, avoiding the need for multiple fixed-voltage converter stages
Data Source
AI summary
A power converter and a circuit arrangement. The power converter has a series circuit, including first and second intermediate circuit capacitors, connected in parallel to first and second half-bridges. A first terminal of a first center switch is connected to a center point of the first half-bridge and is configured to provide a first phase. A first terminal of a second center switch is connected to a center point of the second half-bridge of the power converter and is configured to provide a second phase. A second terminal of the first center switch and of the second center switch are connected and configured to provide a third phase. An evaluation unit is configured to actuate the first and second half-bridges, the first center switch, and the second center switch based on a space vector modulation and to adjust a voltage ratio between the first and second intermediate circuit capacitors.