Three-Level Converter Modular Bridge Arm Design
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Solution Overview
Problem
Current high-power frequency converters are bulky, inefficient, and costly due to the use of phase-shifting transformers and high-voltage semiconductor components, with high energy loss and reliability issues, and existing 2-level converters have inferior maintainability and high manufacturing costs.
Innovation Solution
A three-level converter design featuring modularized structure with series-connected IGBTs and a delta-shaped configuration, utilizing copper or aluminum busbars and insulated wires to reduce stray inductance and commutation loop size, facilitating easier installation and maintenance while minimizing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase-shifting transformer is used to achieve high-voltage frequency conversion, then voltage transformation is achieved, but the transformer is costly and bulky and associated with more energy loss
Solution Approach 1:
The patent extracts and eliminates the phase-shifting transformer from the system by using a three-level converter topology with series-connected low-voltage IGBTs. This removes the bulky transformer component while achieving the same high-voltage frequency conversion function through direct semiconductor switching, thereby reducing energy loss and eliminating the need for expensive transformer equipment.
Solution Approach 2:
The patent replaces expensive high-voltage semiconductor components with cheaper low-voltage IGBTs that can be connected in series. The low-voltage IGBTs are more cost-effective and have lower energy losses compared to traditional high-voltage semiconductors or transformer-based solutions, achieving the same voltage transformation function at lower cost and with improved efficiency.
2Power
If high-voltage semiconductor component is used to achieve high voltage frequency conversion, then voltage conversion is achieved, but the cost of the system is high and associated with higher energy loss
Solution Approach 1:
The patent employs low-voltage IGBTs that are significantly cheaper than high-voltage semiconductor components. By connecting multiple low-voltage IGBTs in series, the system achieves high-voltage frequency conversion at a fraction of the cost of using high-voltage semiconductors, while also reducing energy losses and improving overall system efficiency.
3Ease of manufacture
If 2-level converter with series connection IGBTs is used, then cost is reduced, but the design layout is defective due to inferior maintainability, large commutation loop and high manufacturing cost
Solution Approach 1:
The patent divides the bridge arm into modular units with standardized connection structures. Each module contains specific components (switch units, diode units, busbars, insulated wires) that can be independently assembled and replaced. This modular design greatly improves maintainability by allowing quick replacement of defective modules without disassembling the entire converter, while keeping manufacturing costs low through standardized production processes.
Solution Approach 2:
The patent applies different connection methods to different parts of the circuit: copper busbars are used for high-current paths requiring low resistance, while insulated wires are used for signaling and control circuits. This localized optimization of connection quality reduces overall stray inductance and improves both performance and manufacturability.
4Ease of manufacture
If traditional converter layout is used, then assembly is straightforward, but the commutation loop is large and stray inductance is high
Solution Approach 1:
The patent transitions from a planar layout to a three-dimensional spatial arrangement where upper and lower half-bridge arm circuit modules are disposed side by side and facing each other. This spatial optimization allows the current path to fold back on itself, creating a compact commutation loop that minimizes the enclosed area and thereby reduces stray inductance, while maintaining assembly simplicity through standardized module interfaces.
Data Source
AI summary
A three-level converter includes at least one phase bridge arm, each including an upper-half and a lower-half bridge arm circuit modules. The upper-half bridge arm circuit module includes a first and a second switch units that are in series connection, and a first diode unit. The lower-half bridge arm circuit module includes a third and a fourth switch units that are in series connection, and a second diode unit. The first and second diode units are connected to the neutral point of the capacitor unit; the second and third switch units are connected to the alternating-current terminal; The first and the fourth switch unit is respectively connected to the positive terminal and negative terminal of the direct-current bus; the capacitor unit is connected to the direct-current bus between the positive and negative terminals. The two modules are disposed side by side and facing each other.